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Isotopes of silver
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Isotopes of silver
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Isotopes of silver (47Ag)
Main isotopes[1] Decay
Isotope abun­dance half-life (t1/2) mode pro­duct
105Ag synth 41.29 d ε 105Pd
106mAg synth 8.28 d ε 106Pd
107Ag 51.8% stable
108mAg synth 439 y ε 108Pd
IT 108Ag
109Ag 48.2% stable
110m2Ag synth 249.86 d β− 110Cd
111Ag synth 7.43 d β− 111Cd
Standard atomic weight Ar°(Ag)

Naturally occurring silver (47Ag) is composed of the two stable isotopes 107Ag and 109Ag in almost equal proportions, with 107Ag being slightly more abundant (51.839% natural abundance). Notably, silver is the only element with multiple NMR-active isotopes all having spin 1/2. Thus both 107Ag and 109Ag nuclei produce narrow lines in nuclear magnetic resonance spectra.[4]

40 radioisotopes have been characterized with the most stable being 105Ag with a half-life of 41.29 days, 111Ag with a half-life of 7.43 days, and 112Ag with a half-life of 3.13 hours.

All of the remaining radioactive isotopes have half-lives that are less than an hour, and the majority of these have half-lives that are less than 3 minutes. This element has numerous meta states, with the most stable being 108mAg (half-life 439 years), 110mAg (half-life 249.86 days) and 106mAg (half-life 8.28 days).

Known isotopes of silver range in atomic weight from 92Ag to 132Ag. The primary decay mode before the most abundant stable isotope, 107Ag, is electron capture and the primary mode after is beta decay. The primary decay products before 107Ag are palladium (element 46) isotopes and the primary products after are cadmium (element 48) isotopes.

The palladium isotope 107Pd decays by beta emission to 107Ag with a half-life of 6.5 million years. Iron meteorites are the only objects with a high enough palladium/silver ratio to yield measurable variations in 107Ag abundance. Radiogenic 107Ag was first discovered in the Santa Clara meteorite in 1978.

The discoverers[who?] suggest that the coalescence and differentiation of iron-cored small planets may have occurred 10 million years after a nucleosynthetic event. 107Pd versus 107Ag correlations observed in bodies, which have clearly been melted since the accretion of the Solar System, must reflect the presence of live short-lived nuclides in the early Solar System.

List of isotopes

[edit]


Nuclide
[n 1] 		Z N Isotopic mass (Da)[5]
[n 2][n 3] 		Half-life[1]
[n 4] 		Decay
mode[1]
[n 5] 		Daughter
isotope
[n 6][n 7] 		Spin and
parity[1]
[n 8][n 4] 		Natural abundance (mole fraction)
Excitation energy[n 4] Normal proportion[1] Range of variation
92Ag 47 45 91.95971(43)# 1# ms
[>400 ns] 		β+? 92Pd
p? 91Pd
93Ag 47 46 92.95019(43)# 228(16) ns β+? 93Pd 9/2+#
p? 92Pd
β+, p? 92Rh
94Ag 47 47 93.94374(43)# 27(2) ms β+ (>99.8%) 94Pd 0+#
β+, p (<0.2%) 93Rh
94m1Ag 1350(400)# keV 470(10) ms β+ (83%) 94Pd (7+)
β+, p (17%) 93Rh
94m2Ag 6500(550)# keV 400(40) ms β+ (~68.4%) 94Pd (21+)
β+, p (~27%) 93Rh
p (4.1%) 93Pd
2p (0.5%) 92Rh
95Ag 47 48 94.93569(43)# 1.78(6) s β+ (97.7%) 95Pd (9/2+)
β+, p (2.3%) 94Rh
95m1Ag 344.2(3) keV <0.5 s IT 95Ag (1/2−)
95m2Ag 2531.3(15) keV <16 ms IT 95Ag (23/2+)
95m3Ag 4860.0(15) keV <40 ms IT 95Ag (37/2+)
96Ag 47 49 95.93074(10) 4.45(3) s β+ (95.8%) 96Pd (8)+
β+, p (4.2%) 95Rh
96m1Ag[n 9] 0(50)# keV 6.9(5) s β+ (85.1%) 96Pd (2+)
β+, p (14.9%) 95Rh
96m2Ag 2461.4(3) keV 103.2(45) μs IT 96Ag (13−)
96m3Ag 2686.7(4) keV 1.561(16) μs IT 96Ag (15+)
96m4Ag 6951.8(14) keV 132(17) ns IT 96Ag (19+)
97Ag 47 50 96.923881(13) 25.5(3) s β+ 97Pd (9/2)+
97mAg 620(40) keV 100# ms IT? 97Ag 1/2−#
98Ag 47 51 97.92156(4) 47.5(3) s β+ 98Pd (6)+
β+, p (.0012%) 97Rh
98mAg 107.28(10) keV 161(7) ns IT 98Ag (4+)
99Ag 47 52 98.917646(7) 2.07(5) min β+ 99Pd (9/2)+
99mAg 506.2(4) keV 10.5(5) s IT 99Ag (1/2−)
100Ag 47 53 99.916115(5) 2.01(9) min β+ 100Pd (5)+
100mAg 15.52(16) keV 2.24(13) min IT? 100Ag (2)+
β+? 100Pd
101Ag 47 54 100.912684(5) 11.1(3) min β+ 101Pd 9/2+
101mAg 274.1(3) keV 3.10(10) s IT 101Ag (1/2)−
102Ag 47 55 101.911705(9) 12.9(3) min β+ 102Pd 5+
102mAg 9.40(7) keV 7.7(5) min β+ (51%) 102Pd 2+
IT (49%) 102Ag
103Ag 47 56 102.908961(4) 65.7(7) min β+ 103Pd 7/2+
103mAg 134.45(4) keV 5.7(3) s IT 103Ag 1/2−
104Ag 47 57 103.908624(5) 69.2(10) min β+ 104Pd 5+
104mAg 6.90(22) keV 33.5(20) min β+ (>99.93%) 104Pd 2+
IT (<0.07%) 104Ag
105Ag 47 58 104.906526(5) 41.29(7) d β+ 105Pd 1/2−
105mAg 25.468(16) keV 7.23(16) min IT (99.66%) 105Ag 7/2+
β+ (.34%) 105Pd
106Ag 47 59 105.906663(3) 23.96(4) min β+ 106Pd 1+
β−? 106Cd
106mAg 89.66(7) keV 8.28(2) d β+ 106Pd 6+
IT? 106Ag
107Ag[n 10] 47 60 106.9050915(26) Stable 1/2− 0.51839(8)
107mAg 93.125(19) keV 44.3(2) s IT 107Ag 7/2+
108Ag[6] 47 61 107.9059502(26) 2.382(11) min β− (97.15%) 108Cd 1+
EC (2.57%) 108Pd
β+ (0.283%)
108mAg[6] 109.466(7) keV 439(9) y EC (91.3%) 108Pd 6+
IT (8.7%) 108Ag
109Ag[n 11] 47 62 108.9047558(14) Stable 1/2− 0.48161(8)
109mAg[n 11] 88.0337(10) keV 39.79(21) s IT 109Ag 7/2+
110Ag 47 63 109.9061107(14) 24.56(11) s β− (99.70%) 110Cd 1+
EC (0.30%) 110Pd
110m1Ag 1.112(16) keV 660(40) ns IT 110Ag 2−
110m2Ag 117.59(5) keV 249.863(24) d β− (98.67%) 110Cd 6+
IT (1.33%) 110Ag
111Ag[n 11] 47 64 110.9052968(16) 7.433(10) d β− 111Cd 1/2−
111mAg 59.82(4) keV 64.8(8) s IT (99.3%) 111Ag 7/2+
β− (0.7%) 111Cd
112Ag 47 65 111.9070485(26) 3.130(8) h β− 112Cd 2(−)
113Ag 47 66 112.906573(18) 5.37(5) h β− 113mCd 1/2−
113mAg 43.50(10) keV 68.7(16) s IT (64%) 113Ag 7/2+
β− (36%) 113Cd
114Ag 47 67 113.908823(5) 4.6(1) s β− 114Cd 1+
114mAg 198.9(10) keV 1.50(5) ms IT 114Ag (6+)
115Ag 47 68 114.908767(20) 20.0(5) min β− 115mCd 1/2−
115mAg 41.16(10) keV 18.0(7) s β− (79.0%) 115Cd 7/2+
IT (21.0%) 115Ag
116Ag 47 69 115.911387(4) 3.83(8) min β− 116Cd (0−)
116m1Ag 47.90(10) keV 20(1) s β− (93%) 116Cd (3+)
IT (7%) 116Ag
116m2Ag 129.80(22) keV 9.3(3) s β− (92%) 116Cd (6−)
IT (8%) 116Ag
117Ag 47 70 116.911774(15) 73.6(14) s β− 117mCd 1/2−#
117mAg 28.6(2) keV 5.34(5) s β− (94.0%) 117mCd 7/2+#
IT (6.0%) 117Ag
118Ag 47 71 117.9145955(27) 3.76(15) s β− 118Cd (2−)
118m1Ag 45.79(9) keV ~0.1 μs IT 118Ag (1,2)−
118m2Ag 127.63(10) keV 2.0(2) s β− (59%) 118Cd (5+)
IT (41%) 118Ag
118m3Ag 279.37(20) keV ~0.1 μs IT 118Ag (3+)
119Ag 47 72 118.915570(16) 2.1(1) s β− 119Cd (7/2+)
119mAg 33.5(3) keV[7] 6.0(5) s β− 119Cd (1/2−)
120Ag 47 73 119.918785(5) 1.52(7) s β− 120Cd 4(+)
β−, n (<.003%) 119Cd
120m1Ag[n 9] 0(50)# keV 940(100) ms β−? 120Cd (0−, 1−)
IT? 120Ag
β−, n? 119Cd
120m2Ag 203.2(2) keV 384(22) ms IT (68%) 120Sn 7(−)
β− (32%) 120Cd
β−, n? 119Cd
121Ag 47 74 120.920125(13) 777(10) ms β− (99.92%) 121Cd 7/2+#
β−, n (0.080%) 120Cd
122Ag[8] 47 75 121.9235420(56) 550(50) ms β− 122Cd (1−)
β−, n? 121Cd
122m1Ag[8] 303.7(50) keV 200(50) ms β− 122Cd (9−)
β−, n? 121Cd
IT? 122Ag
122m2Ag 171(50)# keV 6.3(1) μs IT 122Ag (1+)
123Ag 47 76 122.92532(4) 294(5) ms β− (99.44%) 123Cd (7/2+)
β−, n (0.56%) 122Cd
123m1Ag 59.5(5) keV 100# ms β− 123Cd (1/2−)
β−, n? 122Cd
123m2Ag 1450(14)# keV 202(20) ns IT 123Ag
123m3Ag 1472.8(8) keV 393(16) ns IT 123Ag (17/2−)
124Ag 47 77 123.9289318(74)[9] 177.9(26) ms β− (98.7%) 124Cd (2−)
β−, n (1.3%) 123Cd
124m1Ag 188.2(25) keV[9] 144(20) ms β− 124Cd (8−)[9]
β−, n? 123Cd
124m2Ag 155.6(5) keV 140(50) ns IT 124Ag (1+)
124m3Ag 231.1(7) keV 1.48(15) μs IT 124Ag (1−)
125Ag 47 78 124.9310029(43)[9] 160(5) ms β− (88.2%) 125Cd (9/2+)
β−, n (11.8%) 124Cd
125m1Ag 97.1(5) keV 50# ms β−? 125Cd (1/2−)
IT? 125Ag
β−, n? 124Cd
125m2Ag 1501.2(6) keV 491(20) ns IT 125Ag (17/2−)
126Ag 47 79 125.93481(22)# 52(10) ms β− (86.3%) 126Cd 3+#
β−, n (13.7%) 125Cd
126m1Ag 100(100)# keV 108.4(24) ms β− 126Cd 9−#
IT? 126Ag
β−, n? 125Cd
126m2Ag 254.8(5) keV 27(6) μs IT 126Ag 1−#
127Ag 47 80 126.93704(22)# 89(2) ms β− (85.4%) 127Cd (9/2+)
β−, n (14.6%) 126Cd
127mAg 1938(17) keV 67.5(9) ms β− (91.2%) 127Cd (27/2+)
IT (8.8%) 127Ag
128Ag 47 81 127.94127(32)# 54(4) ms[10] β− (80%) 128Cd (9−)[10]
β−, n (20%) 127Cd
β−, 2n? 126Cd
128mAg[10] 2053.9+Z keV 1.60(7) μs IT 128Ag (16−)
129Ag 47 82 128.94432(43)# 49.9(35) ms β− (>80%) 129Cd 9/2+#
β−, n (<20%) 128Cd
130Ag 47 83 129.95073(46)# 40.6(45) ms β− 130Cd 1−#
β−, n? 129Cd
β−, 2n? 128Cd
131Ag 47 84 130.95625(54)# 35(8) ms β− (90%) 131Cd 9/2+#
β−, 2n (10%) 129Cd
β−, n? 130Cd
132Ag 47 85 131.96307(54)# 30(14) ms β− 132Cd 6−#
β−, n? 131Cd
β−, 2n? 130Cd
This table header & footer:
  1. ^ mAg – Excited nuclear isomer.
  2. ^ ( ) – Uncertainty (1σ) is given in concise form in parentheses after the corresponding last digits.
  3. ^ # – Atomic mass marked #: value and uncertainty derived not from purely experimental data, but at least partly from trends from the Mass Surface (TMS).
  4. ^ a b c # – Values marked # are not purely derived from experimental data, but at least partly from trends of neighboring nuclides (TNN).
  5. ^ Modes of decay:
    EC: Electron capture


    IT: Isomeric transition
    n: Neutron emission
    p: Proton emission
  6. ^ Bold italics symbol as daughter – Daughter product is nearly stable.
  7. ^ Bold symbol as daughter – Daughter product is stable.
  8. ^ ( ) spin value – Indicates spin with weak assignment arguments.
  9. ^ a b Order of ground state and isomer is uncertain.
  10. ^ Used to date certain events in the early history of the Solar System
  11. ^ a b c Fission product

See also

[edit]

Daughter products other than silver

References

[edit]
Revisions and contributorsEdit on WikipediaRead on Wikipedia

Isotopes of silver

View on Grokipedia
from Grokipedia
Silver ( 47) has two isotopes, ¹⁰⁷Ag and ¹⁰⁹Ag, which together comprise all naturally occurring silver with atomic masses of 106.905092 u and 108.904757 u, respectively, and natural abundances of 51.84% and 48.16%. In total, 38 isotopes of silver have been discovered so far, including the two ones, 15 proton-rich isotopes, and 21 neutron-rich isotopes, with mass numbers ranging from 92 to 132. Both isotopes possess a nuclear spin of ½ and negative magnetic moments of -0.1135 μₙ and -0.1305 μₙ, respectively. The radioactive isotopes of silver primarily decay via beta minus emission for neutron-rich nuclides and electron capture or beta plus decay for proton-rich ones, with half-lives spanning from microseconds to years. Notable radioactive isotopes include ¹⁰⁸Agᵐ, a long-lived metastable state with a half-life of approximately 418 years, often produced in nuclear reactors and relevant for fission product studies. Other isotopes, such as ¹⁰³Ag (half-life 1.10 hours) and ¹¹¹Ag (half-life 7.47 days), are generated via neutron activation or charged-particle reactions and find applications in medical imaging and therapy, including Auger electron emitters for targeted radiotherapy. Silver isotopes are also significant in and , where variations in isotopic ratios can trace processes or environmental contamination, though natural variations are minimal due to the stability of the dominant isotopes. The evaluation of neutron cross-sections for ¹⁰⁷Ag and ¹⁰⁹Ag supports their use in reactor dosimetry and activation analysis.

Fundamentals of Silver Isotopes

Atomic and Nuclear Properties

Silver has an of 47, meaning its nuclei contain 47 protons, with the number of neutrons varying to produce different isotopes. 38 isotopes of silver are known, spanning mass numbers from 93 to 130. Among these, only two isotopes, ^{107}Ag and ^{109}Ag, are stable, while the remaining are radioactive with half-lives ranging from fractions of a second to several years. The stability of silver isotopes is closely tied to the neutron-to-proton (N/) ratio, which for the stable isotopes is approximately 1.28 in ^{107}Ag (60 neutrons) and 1.32 in ^{109}Ag (62 neutrons). Isotopes with mass numbers near 107–109 exhibit the greatest stability due to favorable N/ ratios that minimize the nucleus's relative to potential decay products. Deviations from this range lead to instability, with proton-rich isotopes (lower A) tending toward or beta-plus decay, and neutron-rich ones (higher A) favoring beta-minus decay. Nuclear binding energies for silver isotopes reflect the trends in this mass region, where the per is roughly 8.5 MeV, contributing to overall stability around A ≈ 107–109. The total BE of a silver nucleus is conceptually given by BE=[Zmp+(A−Z)mn−M]c2BE = \left[ Z m_p + (A - Z) m_n - M \right] c^2 where Z = 47 is the , A is the , m_p and m_n are the masses of the proton and , M is the mass of the nucleus, and c is the . This expression highlights how the mass defect determines the energy required to disassemble the nucleus into its constituent . per decreases slightly for isotopes farther from the stable line, influencing their decay pathways.

Isotopic Notation and Identification

Silver isotopes are denoted using the standard nuclide notation, where the AA (total number of protons and neutrons) is placed as a left superscript before the Ag, with the Z=47Z = 47 optionally included as a left subscript (e.g., 47107Ag^{107}_{47}\mathrm{Ag} or simply 107Ag^{107}\mathrm{Ag} for silver-107). This notation uniquely identifies each by its mass number, distinguishing it from the 38 known isotopes of silver, which range from 93Ag^{93}\mathrm{Ag} to 130Ag^{130}\mathrm{Ag}. Both stable isotopes, 107Ag^{107}\mathrm{Ag} and 109Ag^{109}\mathrm{Ag}, possess a I=1/2I = 1/2, a property that facilitates their characterization in spectroscopic techniques. Identification of silver isotopes relies on high-precision analytical methods tailored to their nuclear and atomic properties. , particularly multicollector (MC-ICP-MS) and (TIMS), is the primary technique for determining isotopic abundances and ratios, enabling detection of trace-level variations in samples from geological or environmental sources. These methods resolve isotopes based on their mass-to-charge ratios, providing quantitative data essential for applications in and nuclear forensics. Nuclear magnetic resonance (NMR) spectroscopy serves as a complementary tool for structural and environmental analysis of silver isotopes, exploiting their NMR-active nuclei. Both 107Ag^{107}\mathrm{Ag} (with gyromagnetic ratio γ=1.723\gamma = 1.723 MHz/T) and 109Ag^{109}\mathrm{Ag} (γ=1.981\gamma = 1.981 MHz/T) yield sharp, narrow lines due to the absence of a quadrupole moment from their spin-1/2 configuration, allowing chemical shift measurements over a range of approximately 1500 ppm. This makes silver unique among elements with multiple isotopes, as it is the only one featuring two spin-1/2 NMR-active isotopes in natural abundance. In mass spectrometric analyses, silver isotopes require distinction from isobars—nuclides of the same but different atomic numbers, such as those from (Z=46Z=46) and (Z=48Z=48). For instance, 107Ag^{107}\mathrm{Ag} may overlap with 107Pd^{107}\mathrm{Pd} or 107Cd^{107}\mathrm{Cd}, while 109Ag^{109}\mathrm{Ag} shares mass with 109Pd^{109}\mathrm{Pd} and 109Cd^{109}\mathrm{Cd}; such interferences are mitigated through prior chemical separation via or by employing high-resolution to resolve the subtle mass differences. These distinctions are critical in multi-element analyses, such as those of meteoritic materials, where Pd, Ag, and Cd abundances are determined simultaneously via techniques.

Natural Occurrence and Abundance

Primordial Isotopes

The primordial isotopes of silver are the stable nuclides 107Ag^{107}\mathrm{Ag} and 109Ag^{109}\mathrm{Ag}, which originated from processes, primarily the p-process in core-collapse supernovae, prior to the formation of the Solar System approximately 4.6 billion years ago. These isotopes were present in the and incorporated into the that collapsed to form the Sun and planets, persisting unchanged due to their stability against . Unlike short-lived radionuclides, 107Ag^{107}\mathrm{Ag} and 109Ag^{109}\mathrm{Ag} represent the baseline isotopic reservoir of silver in primordial Solar System materials. In the early Solar System, 107Ag^{107}\mathrm{Ag} acquired an additional radiogenic component from the beta decay of the extinct radionuclide 107Pd^{107}\mathrm{Pd}, which had a half-life of 6.5 million years and was produced in late nucleosynthetic such as explosions. for live 107Pd^{107}\mathrm{Pd} comes from iron meteorites, where excesses of 107Ag^{107}\mathrm{Ag} (up to several percent relative to 109Ag^{109}\mathrm{Ag}) correlate positively with palladium concentrations, indicating decay occurred within the first few million years after Solar System formation. No traces of 107Pd^{107}\mathrm{Pd} remain in modern samples, as its half-life is negligible compared to the Solar System's age, leaving only the stable daughter isotope to record this early chronometric signal. On , the primordial silver isotopes exhibit uniform distribution in terrestrial ores, with the 107Ag/109Ag^{107}\mathrm{Ag}/^{109}\mathrm{Ag} ratio showing no significant variations attributable to genetic environment, mineralization age, or host rock in hypogene deposits. This lack of mass-dependent preserves the initial Solar System signature through geological processes, including accretion and differentiation. The overall natural isotopic abundances are approximately 51.84% for 107Ag^{107}\mathrm{Ag} and 48.16% for 109Ag^{109}\mathrm{Ag}.

Isotopic Composition in Nature

In nature, silver consists primarily of two stable isotopes: silver-107 (¹⁰⁷Ag) and silver-109 (¹⁰⁹Ag), with standard atomic abundances of 51.839(3)% for ¹⁰⁷Ag and 48.161(3)% for ¹⁰⁹Ag, as determined by the Commission on Isotopic Abundances and Atomic Weights (CIAW) of the International Union of Pure and Applied Chemistry (IUPAC). These values are based on measurements of well-characterized terrestrial samples and serve as the accepted baseline for the element's isotopic composition. Natural variations in silver's isotopic ratios are generally small and arise from mass-dependent processes. In primary (hypogene) ore deposits, such as those involving native silver or , isotopic deviations from the standard ratios are negligible, typically ranging from -0.4‰ to +0.4‰ in δ¹⁰⁹Ag notation, with no significant differences attributable to deposit type, age, or host rock. Minor can occur in biological systems or , such as the formation and dissolution of silver nanoparticles, leading to shifts in the ¹⁰⁹Ag/¹⁰⁷Ag ratio on the order of 1‰ or less under environmental conditions. There are no notable cosmogenic contributions to silver's natural isotopic inventory, as production of Ag isotopes via interactions is insignificant compared to primordial abundances. Precise measurement of silver's isotopic composition relies on standardized materials and analytical techniques that account for . The NIST Standard Reference Material (SRM) 978a, a sample, defines the zero-point for δ¹⁰⁹Ag values, enabling high-precision multicollector (MC-ICPMS) analyses with uncertainties below 0.1‰. These methods correct for mass-dependent fractionation during ionization and detection, ensuring accurate reporting of subtle variations relative to the .

Stable Isotopes

Silver-107

Silver-107 (¹⁰⁷Ag) is one of the two stable of silver, with an of 106.90509(2) u. It has a nuclear spin of 1/2 and a moment of -0.11352(5) μ_N, making it suitable for (NMR) studies due to its configuration that produces narrow spectral lines. In natural silver, ¹⁰⁷Ag has an abundance of 51.839(8)%. The lower atomic mass of ¹⁰⁷Ag compared to the heavier stable isotope contributes to a slightly reduced average atomic mass and thus a marginally lower density for bulk natural silver relative to a sample enriched in heavier isotopes. Additionally, ¹⁰⁷Ag exhibits a thermal neutron capture cross-section of approximately 38 barns, influencing its behavior in neutron absorption processes. A significant aspect of ¹⁰⁷Ag is its origin as the daughter product of the now-extinct radionuclide palladium-107 (¹⁰⁷Pd), which had a half-life of 6.5 million years and decayed primarily by electron capture to ¹⁰⁷Ag. This relationship forms the basis of the ¹⁰⁷Pd–¹⁰⁷Ag chronometer, widely used in cosmochemistry to date early solar system events and metal-silicate fractionation in meteorites.

Silver-109

Silver-109 (¹⁰⁹Ag) is the more massive of silver's two stable isotopes, comprising approximately 48.16% of naturally occurring silver. It possesses an atomic mass of 108.904755 u and a nuclear spin of I = ½⁻, properties that render it magnetically receptive for nuclear magnetic resonance (NMR) spectroscopy. The gyromagnetic ratio of ¹⁰⁹Ag is -1.250 × 10⁷ rad T⁻¹ s⁻¹, which, combined with its spin-½ nature and lack of quadrupole moment, enables the observation of narrow spectral lines in NMR studies of silver-containing compounds, often preferred over ¹⁰⁷Ag due to its slightly higher sensitivity. Unlike ¹⁰⁷Ag, which exhibits isotopic anomalies attributable to the decay of the now-extinct short-lived radionuclide ¹⁰⁷Pd (half-life 6.5 million years) in the early solar system, ¹⁰⁹Ag shows no such excesses and is considered purely primordial, originating directly from nucleosynthetic processes without contributions from radioactive parent decay. This distinction makes ¹⁰⁹Ag a key reference isotope in cosmochemical investigations of silver fractionation in meteorites and planetary materials. In terms of nuclear interactions, ¹⁰⁹Ag exhibits a notably higher thermal neutron capture cross-section of approximately 90 barns for the ¹⁰⁹Ag(n,γ)¹¹⁰Ag reaction, compared to about 38 barns for ¹⁰⁷Ag. This elevated value, derived from evaluated nuclear data libraries, influences absorption and reactivity in environments involving silver, such as nuclear where trace silver impurities can impact economy and fuel burnup calculations. The cross-section's magnitude underscores ¹⁰⁹Ag's role in neutronics modeling, contributing to more accurate simulations of behavior under fluxes.

Radioactive Isotopes

Long-Lived Isotopes

Long-lived isotopes of silver refer to the radioactive nuclides of this element with half-lives greater than one day, distinguishing them from short-lived variants and enabling potential uses in research and applications where extended decay times are beneficial. These isotopes are produced artificially and exhibit decay behaviors influenced by their position relative to the stable isotopes ¹⁰⁷Ag and ¹⁰⁹Ag. Proton-rich isotopes (those with mass numbers below 107) typically undergo electron capture (EC) or positron emission (β⁺) to form palladium daughters, while neutron-rich isotopes (mass numbers above 109) decay primarily via beta-minus (β⁻) emission to cadmium daughters. This dichotomy arises from the nuclear imbalance in proton-to-neutron ratios, with EC/β⁺ reducing proton number and β⁻ increasing it. Among the key examples, ¹⁰⁵Ag possesses a half-life of 41.29 ± 0.07 days and decays exclusively by EC/β⁺ to ¹⁰⁵Pd, with a total decay energy (Q-value) of 1.347 ± 0.005 MeV; this makes it one of the longest-lived neutron-deficient silver isotopes. Similarly, ¹¹¹Ag has a half-life of 7.45 ± 0.01 days and decays 100% by β⁻ emission to ¹¹¹Cd, releasing 1.0368 ± 0.0014 MeV. A particularly remarkable case is the isomeric state ¹⁰⁸mAg, with a half-life of 448 ± 27 years, which decays predominantly by EC/β⁺ (91.3 ± 0.9%) to ¹⁰⁸Pd and by isomeric transition (IT, 8.7 ± 0.9%) to the ground state ¹⁰⁸Ag; its extended longevity stems from the hindered nature of the high-spin excited state. Another significant isomer, ¹¹⁰mAg, exhibits a half-life of 249.83 ± 0.04 days, decaying via β⁻ (primarily to ¹¹⁰Cd) and IT to ¹¹⁰Ag. These properties highlight the diversity in decay pathways for long-lived silver radioisotopes, often involving gamma emission alongside particle decay for de-excitation. The following table summarizes selected long-lived silver isotopes, focusing on their half-lives, primary decay modes, daughter products, and Q-values where established:
IsotopeHalf-lifeDecay Mode(s)Daughter(s)Q-value (MeV)
¹⁰⁵Ag41.29 dEC/β⁺ (100%)¹⁰⁵Pd1.347
¹⁰⁶mAg8.28 dEC/β⁺ (100%)¹⁰⁶Pd3.984
¹⁰⁸mAg448 yEC/β⁺ (91%), IT (9%)¹⁰⁸Pd, ¹⁰⁸Ag1.353
¹¹⁰mAg249.8 dβ⁻ (~90%), IT (~10%)¹¹⁰Cd, ¹¹⁰Ag2.647
¹¹¹Ag7.45 dβ⁻ (100%)¹¹¹Cd1.037
Data derived from evaluated nuclear structure databases, emphasizing representative examples rather than exhaustive listings.

Short-Lived Isotopes

Short-lived isotopes of silver refer to the radioactive nuclides of this element with half-lives shorter than 24 hours, which are valuable for investigating rapid nuclear decay processes, short-lived excited states, and transient phenomena in nuclear reactions due to their quick disappearance. These isotopes occur across a broad mass range, from proton-rich lighter variants decaying mainly through (EC) or (β⁺) to neutron-rich heavier ones favoring β⁻ decay, often accompanied by gamma emission for spectroscopic studies. Many exhibit half-lives below 3 minutes, allowing researchers to probe nuclear structure and beta-delayed processes in real-time experiments. On the proton-rich side, isotopes from ^{93}Ag to ^{104}Ag are exclusively short-lived, with decay characteristics suited to studies of and physics in neutron-deficient nuclei. For example, ^{94}Ag decays with a of 26 milliseconds primarily via EC/β⁺ (100%), while ^{104}Ag has a of 69.2 minutes, decaying via EC/β⁺ (100%) and emitting key positrons and gamma rays useful for (PET) imaging research. Neutron-rich short-lived silver isotopes, spanning ^{110}Ag to ^{132}Ag (excluding longer-lived ground states like ^{111}Ag), predominantly undergo β⁻ decay, enabling investigations into beta-delayed and shell effects in the region. Representative examples include ^{110}Ag, with a 24.6-second decaying mainly by β⁻ (99.7%) to stable ^{110}Cd, and ^{112}Ag, which has a 3.13-hour and decays 100% via β⁻ to ^{112}Cd, providing insights into high-spin states through its gamma transitions. Similarly, ^{113}Ag decays by β⁻ (100%) with a of 5.37 hours. Beyond these, isotopes from ^{114}Ag to ^{132}Ag feature progressively shorter , from 4.6 seconds for ^{114}Ag (β⁻, 100%) down to 28 milliseconds for ^{132}Ag (β⁻, 100%), often with minor β⁻-delayed branches that inform astrophysical r-process models. Certain isomers, such as ^{110m2}Ag with a of 249.86 days, contrast with short-lived ground states but contribute to understanding isomeric transitions in silver; however, the focus remains on the fleeting ground and low-lying states for dynamic decay studies. The following table summarizes , principal decay modes, and key branching ratios for selected short-lived silver isotopes in the specified mass ranges (ground states unless noted; data exclude stable and long-lived nuclides >24 hours). Proton-rich (^{93}Ag to ^{104}Ag):
IsotopeHalf-lifePrincipal decay modeBranching ratios
^{93}Ag228 nsEC/β⁺100%
^{94}Ag26 msEC/β⁺100%
^{95}Ag1.75 sEC/β⁺100%
^{96}Ag4.40 sEC/β⁺91.5% (EC/β⁺), 8.5% (EC,p)
^{97}Ag25.5 sEC100%
^{98}Ag47.5 sEC/β⁺~100% (minor EC,p ~0.001%)
^{99}Ag2.07 minEC100%
^{100}Ag2.01 minEC100%
^{101}Ag11.1 minEC100%
^{102}Ag12.9 minEC100%
^{103}Ag65.7 minEC/β⁺100%
^{104}Ag69.2 minEC/β⁺100%
Neutron-rich short-lived subset (^{110}Ag to ^{132}Ag, half-lives <24 h):
IsotopeHalf-lifePrincipal decay modeBranching ratios
^{110}Ag24.6 sβ⁻99.7% (β⁻), 0.3% (EC)
^{112}Ag3.13 hβ⁻100%
^{113}Ag5.37 hβ⁻100%
^{114}Ag4.6 sβ⁻100%
^{115}Ag^m18.0 sβ⁻79% (β⁻), 21% (IT)
^{116}Ag230 sβ⁻100%
^{118}Ag3.76 sβ⁻100%
^{120}Ag1.23 sβ⁻>99.997% (β⁻), <0.003% (β⁻,n)
^{122}Ag0.53 sβ⁻99.8% (β⁻), 0.2% (β⁻,n)
^{125}Ag0.16 sβ⁻Predominantly β⁻, minor β⁻,n
^{130}Ag42 msβ⁻Predominantly β⁻, minor β⁻,n/2n
^{132}Ag28 msβ⁻100% (β⁻), minor multi-neutron branches

Production and Synthesis

Natural Production Processes

The stable isotopes of silver, ^{107}Ag and ^{109}Ag, which constitute the primordial abundance in the solar system, were primarily formed through neutron-capture processes in stars prior to the collapse of the molecular cloud that gave rise to our solar system approximately 4.6 billion years ago. In stellar nucleosynthesis, these isotopes arise mainly from the rapid neutron-capture process (r-process), which accounts for roughly 80% of the solar system's silver abundance, with the majority originating from the weak r-process component occurring in explosive astrophysical events such as core-collapse supernovae or neutron star mergers at intermediate neutron densities. The remaining fraction, approximately 20%, is attributed to the slow neutron-capture process (s-process) in the helium- and carbon-burning shells of low-mass asymptotic giant branch (AGB) stars, where neutrons from reactions like ^{13}C(α,n)^{16}O are captured slowly by seed nuclei, allowing β-decays to compete and build up toward silver. The r-process also contributes to the production of radioactive silver isotope precursors, such as neutron-rich species beyond N=50, which undergo subsequent β-decays to populate the stable silver isotopes or nearby chains in the valley of stability. On Earth, additional natural production of silver isotopes occurs through terrestrial processes, though at negligible levels compared to the primordial inventory. The radioactive isotope ^{108}Ag is generated cosmogenically via spallation reactions induced by cosmic-ray protons and neutrons interacting with stable silver or palladium nuclei in the upper atmosphere and surface rocks, with production rates on the order of atoms per gram per year but resulting in abundances far below 10^{-12} relative to stable silver. Spontaneous fission of heavy actinides like ^{238}U in natural ores can rarely yield silver isotopes through asymmetric fission channels, leading to minor isotopic anomalies in uranium-rich minerals such as uraninite, but this contributes insignificantly to overall natural abundances.

Artificial Production Methods

Artificial production of silver isotopes primarily involves nuclear reactions in reactors or accelerators to generate radioactive variants, and physical separation techniques to enrich stable isotopes beyond their natural abundances. These methods enable the creation of isotopes not readily available in nature, such as short-lived radioisotopes for research or enriched stable forms for tracing studies. Neutron activation is a key technique for producing certain silver isotopes, particularly by irradiating palladium targets in nuclear reactors. For instance, silver-109 can be obtained through the neutron capture reaction on palladium-108, where ¹⁰⁸Pd captures a neutron to form ¹⁰⁹Pd, which subsequently decays via beta emission to ¹⁰⁹Ag (stable) after passing through the short-lived ¹⁰⁹ᵐAg metastable state (half-life 39.6 seconds). This route is valuable for generating stable ¹⁰⁹Ag for use as tracers, with yields depending on the enrichment of the ¹⁰⁸Pd target and neutron flux, typically achieved in thermal neutron reactors like TRIGA facilities. Similarly, silver-111 (half-life 7.45 days) is produced via the ¹¹⁰Pd(n,γ)¹¹¹Pd reaction followed by beta decay of ¹¹¹Pd (half-life 23.4 minutes) to ¹¹¹Ag, using natural or enriched palladium targets irradiated at fluxes around 10¹²–10¹³ n/cm²·s, resulting in activities up to several GBq after chemical separation. Accelerator-based methods, such as those using , facilitate the production of radioactive silver isotopes through charged-particle induced reactions on targets. Silver-111 is commonly synthesized via the ¹¹⁰Pd(d,n)¹¹¹Ag reaction with deuteron beams of 10–20 MeV energy, offering higher yields than neutron routes for therapeutic quantities (up to 1 GBq per irradiation) due to the direct production path, though it requires post-irradiation separation to remove co-produced radionuclides like ¹¹¹ᵐCd. Proton-induced reactions, such as ¹¹⁰Pd(p,n)¹¹¹Pd → ¹¹¹Ag, are also employed in some facilities, with beam currents of 100–500 μA on enriched targets yielding comparable activities after decay and purification, emphasizing the role of precise energy selection to minimize impurities. These approaches are preferred for on-demand production in medical isotope facilities like ISOLPHARM. For stable silver isotopes (¹⁰⁷Ag and ¹⁰⁹Ag), enrichment is achieved through isotope separation techniques that exploit mass differences. Electromagnetic separation, using calutron devices, ionizes silver atoms and deflects them in a magnetic field, allowing collection of enriched fractions; this method, historically developed at Oak Ridge National Laboratory, has produced highly enriched samples (>99%) for research, with separation factors scaling with the 2% mass difference between ¹⁰⁷Ag and ¹⁰⁹Ag. Laser-based methods, such as resonant photo-ionization, selectively excite and ionize one isotope using tuned lasers (e.g., at 331.3 nm for ¹⁰⁷Ag), enabling efficient separation in gas-phase or atomic beams with isotopic selectivities exceeding 1000:1, as demonstrated in collinear setups for precise tracing applications. These techniques are conducted in specialized facilities to achieve enrichments far beyond the natural 51.84% ¹⁰⁷Ag and 48.16% ¹⁰⁹Ag abundances.

Applications and Uses

Scientific and Geochemical Applications

Silver isotopes, particularly the ¹⁰⁷Ag-¹⁰⁷Pd decay system, serve as a key chronometer for dating events in the early Solar System. The extinct ¹⁰⁷Pd, with a of 6.5 million years, decays by beta minus emission to stable ¹⁰⁷Ag, allowing researchers to measure excesses in the ¹⁰⁷Ag/¹⁰⁹Ag ratio in meteoritic materials as evidence of live ¹⁰⁷Pd at the time of parent body formation. This system is especially valuable for iron meteorites, where and silver partition into metallic phases, enabling precise timing of core and differentiation processes that occurred shortly after Solar System formation around 4.57 billion years ago. The first evidence of this system was identified in the Santa Clara iron meteorite, where the ¹⁰⁷Ag/¹⁰⁹Ag ratio was found to be approximately 4% higher than terrestrial values, indicating the presence of undecayed ¹⁰⁷Pd during the meteorite's solidification. Subsequent studies on other meteorites, such as Allende and Hoba, have confirmed these anomalies and refined the initial abundance of ¹⁰⁷Pd, providing constraints on the timing of protoplanetary accretion and volatile element depletion. This approach complements other short-lived isotope systems like ¹⁸²Hf-¹⁸²W, offering insights into the thermal and chemical evolution of asteroidal cores. In , stable silver ratios (¹⁰⁷Ag/¹⁰⁹Ag) are employed as tracers to identify sources of anthropogenic in environmental systems. Variations in these ratios arise from industrial processes like and , which fractionate isotopes differently from natural , allowing differentiation between ore-derived and atmospheric inputs in soils, sediments, and bodies. For instance, silver contamination from non-ferrous metal smelters exhibits distinct isotopic signatures that enable source apportionment in impacted ecosystems, aiding remediation efforts. Nuclear cross-sections for reactions involving silver isotopes contribute to astrophysical models of heavy element . Maxwellian-averaged neutron capture cross-sections on ¹⁰⁷Ag and ¹⁰⁹Ag, measured at stellar energies around 30 keV, are integral to simulations of the in stars, where they influence the production yields of silver and neighboring elements. from compilations like the Karlsruhe Astrophysical Database of Nucleosynthesis in Stars (KADoNiS) provide recommended values, such as 792 ± 30 mb for ¹⁰⁷Ag(n,γ); a recent as of November 2025 reports 887 ± 89 mb.

Medical and Industrial Applications

Silver-111 (¹¹¹Ag), with a of 7.45 days, serves as a promising for due to its emission of beta particles for potential therapy and gamma rays suitable for (SPECT). This theranostic enables the visualization of biodistribution in preclinical models, such as tracking silver-based compounds in for targeted cancer applications. Production via of palladium-110 targets has been optimized, yielding high specific activity for labeling biomolecules. Silver-105 (¹⁰⁵Ag), possessing a of 41.3 days, has been explored in radiotherapy trials through radiolabeling of silver nanoparticles for targeted delivery. These labeled nanoparticles, with sizes around 7-16 nm, facilitate tracing accumulation in organs and enhance precision in therapeutic applications against tumors. In industrial settings, stable silver-109 (¹⁰⁹Ag) is employed in to detect trace silver levels in materials like geological samples and catalysts, aiding and material testing. Additionally, isotopically labeled silver, including radioactive variants, acts as tracers in applications, monitoring the distribution and efficacy of silver nanoparticles in consumer products such as dressings and textiles. For long-lived isotopes like silver-108m (¹⁰⁸mAg), with a of approximately 439 years, handling requires strict adherence to standards to limit exposure. The U.S. specifies annual dose limits of 50 mSv to the whole body and 500 mSv to extremities for workers, emphasizing time, distance, and shielding in manipulation to prevent internal contamination via or .

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