babar_2015#
S. Babar and J. H. Weaver, “Optical constants of Cu, Ag, and Au revisited”, Appl. Opt. 54, 477-481 (2015)
Source record · Catalogue · Review register
DOI: 10.1364/AO.54.000477
Source kind: measurement
Recorded technique: Kramers-Kronig analysis of ‘largely unpublished absorptivity measurements by Weaver et al.’ (p. 477): the quantity measured was the absorptivity A = 1 - R (‘In the infrared, R is nearly 100%, and a measurement of A rather than R provides inherently greater accuracy’), on mechanically polished single crystals, chemically cleaned to remove work damage (as in Weaver et al.’s 1981 compilations, the paper’s Refs. 1-2). ‘JHW’ in the paper is J. H. Weaver (Fig. 1 caption: ‘JHW (J. H. Weaver)’), not Johnson (Johnson and Christy are ‘JC’). To extend the range for the analysis: for Ag, the reflectance of Leveque, Olson and Lynch up to 30 eV (Phys. Rev. B 27, 4654 (1983)); for Cu, the JHW data joined to Johnson and Christy’s and then to Hagemann, Gudat and Kunz’s (HGK) up to 30 eV; above that, power-law extrapolations R = R_o E^-3.5 up to 1000 eV (p. 477). For Au the reflectance (JHW) is ‘the reproduction of the reflectance results in Ref. [2]’ (Fig. 3 caption), i.e. Weaver, Krafka, Lynch and Koch, Optical Properties of Metals II (ZAED, 1981). The range of the analysis reported: 0.1-6 eV (abstract); ‘Extensive comparisons that extend up to 30 eV are available from the Weaver website’ (p. 477).
Materials in structured entries: Ag, Au, Cu
Dataset quantities: extinction_coefficient, permittivity_imaginary, permittivity_real, refractive_index
Contents: 18 datasets; 0 formulas.
Curation notes#
Journal pages 477-481 = PDF pages 1-5; Table 1 and its continuation are on pp. 479-480. Identity checked against the first page.
WHAT IS TABULATED. Table 1 (‘Optical Constants for Cu, Ag, and Au’, pp. 479-480): R, epsilon_1 and epsilon_2 of each metal against the photon energy E, 0.10-6.00 eV (0.05 eV steps to 1.00 eV, then 0.10 eV): 69 rows. The paper calls these ‘the results of the Kramers-Kronig analyses of JHW reflectance data’ (p. 478). Epsilon_1 and epsilon_2 are recorded as printed (one dataset per metal and quantity); R has no quantity and is kept in each row’s printed cells. The paper gives no uncertainty for the tabulated values; it says ‘Kramers-Kronig analyses introduce uncertainties in the magnitudes of the dielectric function, but those are minimized by measurements that scan the wide energy range of 0.1-30 eV’ (p. 479). No temperature is stated. No Drude parameters are given.
SAMPLES. Bulk single crystals (‘mechanically polished single crystals that were chemically cleaned’, p. 477), not evaporated films: no thickness or substrate applies. The paper argues that its single-crystal results ‘are more representative of the metals than the thin-film data’ (p. 479).
COMPARISON WITH JOHNSON AND CHRISTY (JC; figures only, Figs. 1-6 and the supplement). JC used reflection and transmission measurements on 185-500 A films evaporated onto fused quartz at 1e-6 Torr in an oil-pumped bell jar (pp. 478-479), with ‘a large uncertainty in the measured JC optical constants’. Text (pp. 479-480): ‘the magnitudes of those constants are quite different from those of JC. For example, the infrared values for epsilon_2 are lower by a factor of 2-4 for Cu where the greatest departure from bulk-like character is expected. The agreement is much better for Ag ... and intermediate for Au.’ Fig. 1: below about 2 eV the JHW reflectance of Cu is higher than JC’s, HGK’s and Palik’s; Fig. 2: ‘excellent agreement in R between JC and JHW’ for Ag. Palik’s Cu reflectance shows a discontinuity and ‘a typo at ~3’ (Fig. 1 caption). The paper also compares with Palik’s handbook (which reproduces Cu from HGK and others, Ag from Leveque et al., Dold and Mecke, Winsemius et al., and Au from Dold and Mecke, Theye, and Canfield et al.) and with HGK (who reproduce JC and Ehrenreich and Philipp for Cu, JC and Irani et al. for Ag and Au) (pp. 477-478).
SUPPLEMENT (original/source_02, 17 pages; ‘The following tables and figures accompany a manuscript’): figures only. Figs. S1-S7 give n, k, epsilon_1, epsilon_2 and R of Cu, Ag and Au from 0 to 6 eV with JC, Palik and HGK for comparison; Figs. S8-S16 repeat them to 30 eV (JHW n and k to 30 eV in Fig. S15). No numbers are printed, so nothing is taken from it; the 6-30 eV values are in the website file (below).
WEBSITE DATA (datasets web_*). The paper’s ‘Weaver website’ (Ref. 4, p. 477) holds the analysis to 30 eV: the workbook optical-constantsCuAgAu.xlsx, attached to the paper in the library (fetched 2026-09-28 from jhweaver.matse.illinois.edu, with its URL and SHA-256). Its sheet ‘This work’ gives, for each metal in its own block, E (eV), R, n, k, e1 and e2 to five significant figures: Cu 0.10-29.92 eV (169 rows), Ag 0.10-30.42 eV (170), Au 0.10-30.01 eV (168); 0.05 eV steps to 6.10 eV, then 0.5 eV steps (Cu and Ag at 6.42, 6.92 ... ; Au at 6.51, 7.01 ...). n and k are recorded as the primary values and epsilon_1, epsilon_2 as checks (the curators’ convention where both are given; the paper does not say which the analysis produced first: a Kramers-Kronig analysis of A = 1 - R gives the phase, hence N = n + ik); R stays in printed. The workbook displays the numbers rounded (formats 0.00 and 0.000) but stores the five-figure values, which are what is extracted. Checks (2026-09-28): epsilon_1 = n^2 - k^2 and epsilon_2 = 2nk hold in every row of every metal within the bound set by the five printed figures (worst Cu 10.92 eV, 0.96 of the bound; Au 5.75 eV prints e1 = -0.00012672 with n = k = 1.2272), and R = |(N - 1)/(N + 1)|^2 to 2.3e-5 (Ag, 5.95 eV). AGAINST TABLE 1: at all 69 energies of Table 1 (0.10-6.00 eV) the sheet’s R, epsilon_1 and epsilon_2 round to Table 1’s printed values for all three metals, with no exception: Table 1 is this sheet rounded to three decimals in R and two in epsilon. The web datasets therefore repeat Table 1 below 6 eV (the two should not both be used). WHAT LIES ABOVE 6 eV (the paper, p. 477; not measured by Babar and Weaver): for Ag, the analysis used Leveque, Olson and Lynch’s reflectance (Phys. Rev. B 27, 4654 (1983)) up to 30 eV; for Cu, the JHW reflectance joined to Johnson and Christy’s and then to Hagemann, Gudat and Kunz’s (HGK) up to 30 eV; for Au, the reflectance of Weaver et al.’s 1981 compilation (weaver_1981: J. H. Weaver’s electropolished Au(110) at 0.2-4 eV and C. G. Olson and D. W. Lynch’s to 30 eV). Above 30 eV R = R_o E^-3.5 to 1000 eV. So the 6-30 eV rows are Babar and Weaver’s Kramers-Kronig results of other authors’ reflectance (Cu’s partly from films: JC’s 185-500 A films, HGK’s evaporated films), and their magnitudes carry the extrapolation uncertainty the paper describes. The other sheets: ‘JHW-Au-ZAED’ (the gold table of Weaver et al. 1981, curated as weaver_1981), and ‘JC’ (Johnson and Christy, Cu, Ag, Au at 0.64-6.6 eV, 49 rows, E R n k e1 e2), ‘HGK’ (Hagemann et al., 0.1-30 eV) and ‘Palik’ (Palik’s handbook values, 0.125-30 eV): other authors’ values, not extracted here (johnson_1972 and hagemann_1974 are other extractions’ records; the comparison is left to review).
WEBSITE DATA AGAINST OTHER RECORDS (2026-09-28; interpolated). Against werner_2009’s REELS epsilon above 6 eV: Ag at 6 eV N = 1.079 + 1.247i against 0.949 + 1.548i, at 10 eV 1.211 + 0.571i against 1.301 + 0.858i, at 20 eV 1.050 + 0.543i against 1.143 + 0.626i; Cu at 6 eV 1.021 + 1.599i against 0.962 + 1.782i, at 10 eV 1.057 + 0.825i against 1.006 + 1.053i; Au at 6 eV 1.242 + 1.152i against 1.422 + 1.502i, at 20 eV 1.186 + 0.833i against 1.095 + 0.979i. The REELS k is 3-50 % above the website’s between 6 and 20 eV. Against weaver_1981 (the gold reflectance this Au analysis used): the website’s Au epsilon_2 is 2-3 % higher than the 1981 table’s at 2-15 eV (5.753 against 5.590 at 4 eV) and 8-12 % at 0.5-1 eV (2.201 against 2.030 at 1 eV), and |epsilon_1| about 3 % larger below 3 eV (-66.27 against -64.47 at 1 eV): the same reflectance, a different Kramers-Kronig analysis.
REFRACTIVEINDEX.INFO. solprop’s silver table (physdata/data/silver_stitched.csv) takes 0.2066-12.4 um from the database’s Ag/Babar page, i.e. this table converted to n and k (0.1-6.0 eV); see the curators’ notes for the comparison.
Recorded bibliographic identity status: VALIDATED. This concerns identification of the source; it does not establish the scientific correctness of its contents.
Datasets#
babar_2015/eps1_Cu#
{
"id": "eps1_Cu",
"material": "Cu",
"file": "Cu/babar_2015__eps1_Cu.csv",
"table": "tbl_8cb2a14ef702",
"quantity": "permittivity_real",
"abscissa_unit": "eV",
"use": "primary",
"parameters": {
"form": "bulk",
"technique": "Kramers-Kronig analysis of absorptivity (reflectance)"
}
}
Table 1, pp. 479-480 (both parts, tbl_8cb2a14ef702 and tbl_76629faf19ce): epsilon_1 of Cu, 0.10-6.00 eV, 69 rows, as printed (negative below the plasma edge). Kramers-Kronig result; single crystal.
babar_2015/eps2_Cu#
{
"id": "eps2_Cu",
"material": "Cu",
"file": "Cu/babar_2015__eps2_Cu.csv",
"table": "tbl_8cb2a14ef702",
"quantity": "permittivity_imaginary",
"abscissa_unit": "eV",
"use": "primary",
"parameters": {
"form": "bulk",
"technique": "Kramers-Kronig analysis of absorptivity (reflectance)"
}
}
Table 1, pp. 479-480 (both parts): epsilon_2 of Cu, 0.10-6.00 eV, 69 rows, as printed.
babar_2015/eps1_Ag#
{
"id": "eps1_Ag",
"material": "Ag",
"file": "Ag/babar_2015__eps1_Ag.csv",
"table": "tbl_8cb2a14ef702",
"quantity": "permittivity_real",
"abscissa_unit": "eV",
"use": "primary",
"parameters": {
"form": "bulk",
"technique": "Kramers-Kronig analysis of absorptivity (reflectance)"
}
}
Table 1, pp. 479-480 (both parts): epsilon_1 of Ag, 0.10-6.00 eV, 69 rows, as printed. Epsilon_1 crosses zero between 3.80 (-0.33) and 3.90 eV (0.52), and is negative again from 4.70 eV.
babar_2015/eps2_Ag#
{
"id": "eps2_Ag",
"material": "Ag",
"file": "Ag/babar_2015__eps2_Ag.csv",
"table": "tbl_8cb2a14ef702",
"quantity": "permittivity_imaginary",
"abscissa_unit": "eV",
"use": "primary",
"parameters": {
"form": "bulk",
"technique": "Kramers-Kronig analysis of absorptivity (reflectance)"
}
}
Table 1, pp. 479-480 (both parts): epsilon_2 of Ag, 0.10-6.00 eV, 69 rows, as printed (two decimals: 0.20-0.40 between 2 and 3.8 eV, so about 3 % resolution there).
babar_2015/eps1_Au#
{
"id": "eps1_Au",
"material": "Au",
"file": "Au/babar_2015__eps1_Au.csv",
"table": "tbl_8cb2a14ef702",
"quantity": "permittivity_real",
"abscissa_unit": "eV",
"use": "primary",
"parameters": {
"form": "bulk",
"technique": "Kramers-Kronig analysis of absorptivity (reflectance)"
}
}
Table 1, pp. 479-480 (both parts): epsilon_1 of Au, 0.10-6.00 eV, 69 rows, as printed. The Au reflectance is Weaver et al.’s 1981 compilation’s (Ref. 2; Fig. 3 caption).
babar_2015/eps2_Au#
{
"id": "eps2_Au",
"material": "Au",
"file": "Au/babar_2015__eps2_Au.csv",
"table": "tbl_8cb2a14ef702",
"quantity": "permittivity_imaginary",
"abscissa_unit": "eV",
"use": "primary",
"parameters": {
"form": "bulk",
"technique": "Kramers-Kronig analysis of absorptivity (reflectance)"
}
}
Table 1, pp. 479-480 (both parts): epsilon_2 of Au, 0.10-6.00 eV, 69 rows, as printed.
babar_2015/web_n_Cu#
{
"id": "web_n_Cu",
"material": "Cu",
"file": "Cu/babar_2015__web_n_Cu.csv",
"table": "data/optical-constantsCuAgAu.xlsx",
"quantity": "refractive_index",
"abscissa_unit": "eV",
"use": "primary",
"parameters": {
"form": "bulk",
"technique": "Kramers-Kronig analysis of absorptivity (reflectance)"
}
}
Weaver website workbook, sheet ‘This work’, the Cu block: n of Cu, 0.10-29.92 eV, 169 rows, five significant figures as stored. Below 6.05 eV it repeats Table 1 (eps1_Cu, eps2_Cu) to more figures; above 6 eV it rests on other authors’ reflectance (see notes).
babar_2015/web_k_Cu#
{
"id": "web_k_Cu",
"material": "Cu",
"file": "Cu/babar_2015__web_k_Cu.csv",
"table": "data/optical-constantsCuAgAu.xlsx",
"quantity": "extinction_coefficient",
"abscissa_unit": "eV",
"use": "primary",
"parameters": {
"form": "bulk",
"technique": "Kramers-Kronig analysis of absorptivity (reflectance)"
}
}
Weaver website workbook, sheet ‘This work’, the Cu block: k of Cu, 0.10-29.92 eV, 169 rows, five significant figures as stored.
babar_2015/web_eps1_Cu#
{
"id": "web_eps1_Cu",
"material": "Cu",
"file": "Cu/babar_2015__web_eps1_Cu.csv",
"table": "data/optical-constantsCuAgAu.xlsx",
"quantity": "permittivity_real",
"abscissa_unit": "eV",
"use": "check",
"parameters": {
"form": "bulk",
"technique": "Kramers-Kronig analysis of absorptivity (reflectance)"
}
}
Weaver website workbook, sheet ‘This work’, the Cu block: epsilon_1 (e1) of Cu, 0.10-29.92 eV, 169 rows, five significant figures as stored. A check: it repeats n and k (epsilon = N^2) in every row.
babar_2015/web_eps2_Cu#
{
"id": "web_eps2_Cu",
"material": "Cu",
"file": "Cu/babar_2015__web_eps2_Cu.csv",
"table": "data/optical-constantsCuAgAu.xlsx",
"quantity": "permittivity_imaginary",
"abscissa_unit": "eV",
"use": "check",
"parameters": {
"form": "bulk",
"technique": "Kramers-Kronig analysis of absorptivity (reflectance)"
}
}
Weaver website workbook, sheet ‘This work’, the Cu block: epsilon_2 (e2) of Cu, 0.10-29.92 eV, 169 rows, five significant figures as stored. A check: it repeats n and k (epsilon = N^2) in every row.
babar_2015/web_n_Ag#
{
"id": "web_n_Ag",
"material": "Ag",
"file": "Ag/babar_2015__web_n_Ag.csv",
"table": "data/optical-constantsCuAgAu.xlsx",
"quantity": "refractive_index",
"abscissa_unit": "eV",
"use": "primary",
"parameters": {
"form": "bulk",
"technique": "Kramers-Kronig analysis of absorptivity (reflectance)"
}
}
Weaver website workbook, sheet ‘This work’, the Ag block: n of Ag, 0.10-30.42 eV, 170 rows, five significant figures as stored. Below 6.05 eV it repeats Table 1 (eps1_Ag, eps2_Ag) to more figures; above 6 eV it rests on other authors’ reflectance (see notes).
babar_2015/web_k_Ag#
{
"id": "web_k_Ag",
"material": "Ag",
"file": "Ag/babar_2015__web_k_Ag.csv",
"table": "data/optical-constantsCuAgAu.xlsx",
"quantity": "extinction_coefficient",
"abscissa_unit": "eV",
"use": "primary",
"parameters": {
"form": "bulk",
"technique": "Kramers-Kronig analysis of absorptivity (reflectance)"
}
}
Weaver website workbook, sheet ‘This work’, the Ag block: k of Ag, 0.10-30.42 eV, 170 rows, five significant figures as stored.
babar_2015/web_eps1_Ag#
{
"id": "web_eps1_Ag",
"material": "Ag",
"file": "Ag/babar_2015__web_eps1_Ag.csv",
"table": "data/optical-constantsCuAgAu.xlsx",
"quantity": "permittivity_real",
"abscissa_unit": "eV",
"use": "check",
"parameters": {
"form": "bulk",
"technique": "Kramers-Kronig analysis of absorptivity (reflectance)"
}
}
Weaver website workbook, sheet ‘This work’, the Ag block: epsilon_1 (e1) of Ag, 0.10-30.42 eV, 170 rows, five significant figures as stored. A check: it repeats n and k (epsilon = N^2) in every row.
babar_2015/web_eps2_Ag#
{
"id": "web_eps2_Ag",
"material": "Ag",
"file": "Ag/babar_2015__web_eps2_Ag.csv",
"table": "data/optical-constantsCuAgAu.xlsx",
"quantity": "permittivity_imaginary",
"abscissa_unit": "eV",
"use": "check",
"parameters": {
"form": "bulk",
"technique": "Kramers-Kronig analysis of absorptivity (reflectance)"
}
}
Weaver website workbook, sheet ‘This work’, the Ag block: epsilon_2 (e2) of Ag, 0.10-30.42 eV, 170 rows, five significant figures as stored. A check: it repeats n and k (epsilon = N^2) in every row.
babar_2015/web_n_Au#
{
"id": "web_n_Au",
"material": "Au",
"file": "Au/babar_2015__web_n_Au.csv",
"table": "data/optical-constantsCuAgAu.xlsx",
"quantity": "refractive_index",
"abscissa_unit": "eV",
"use": "primary",
"parameters": {
"form": "bulk",
"technique": "Kramers-Kronig analysis of absorptivity (reflectance)"
}
}
Weaver website workbook, sheet ‘This work’, the Au block: n of Au, 0.10-30.01 eV, 168 rows, five significant figures as stored. Below 6.05 eV it repeats Table 1 (eps1_Au, eps2_Au) to more figures; above 6 eV it rests on other authors’ reflectance (see notes).
babar_2015/web_k_Au#
{
"id": "web_k_Au",
"material": "Au",
"file": "Au/babar_2015__web_k_Au.csv",
"table": "data/optical-constantsCuAgAu.xlsx",
"quantity": "extinction_coefficient",
"abscissa_unit": "eV",
"use": "primary",
"parameters": {
"form": "bulk",
"technique": "Kramers-Kronig analysis of absorptivity (reflectance)"
}
}
Weaver website workbook, sheet ‘This work’, the Au block: k of Au, 0.10-30.01 eV, 168 rows, five significant figures as stored.
babar_2015/web_eps1_Au#
{
"id": "web_eps1_Au",
"material": "Au",
"file": "Au/babar_2015__web_eps1_Au.csv",
"table": "data/optical-constantsCuAgAu.xlsx",
"quantity": "permittivity_real",
"abscissa_unit": "eV",
"use": "check",
"parameters": {
"form": "bulk",
"technique": "Kramers-Kronig analysis of absorptivity (reflectance)"
}
}
Weaver website workbook, sheet ‘This work’, the Au block: epsilon_1 (e1) of Au, 0.10-30.01 eV, 168 rows, five significant figures as stored. A check: it repeats n and k (epsilon = N^2) in every row.
babar_2015/web_eps2_Au#
{
"id": "web_eps2_Au",
"material": "Au",
"file": "Au/babar_2015__web_eps2_Au.csv",
"table": "data/optical-constantsCuAgAu.xlsx",
"quantity": "permittivity_imaginary",
"abscissa_unit": "eV",
"use": "check",
"parameters": {
"form": "bulk",
"technique": "Kramers-Kronig analysis of absorptivity (reflectance)"
}
}
Weaver website workbook, sheet ‘This work’, the Au block: epsilon_2 (e2) of Au, 0.10-30.01 eV, 168 rows, five significant figures as stored. A check: it repeats n and k (epsilon = N^2) in every row.
Formulas#
No formulas are recorded.
Corrections#
No dataset errata are recorded in this source record.
Formula corrections, where recorded, appear with their formulas above. Curation notes may also discuss corrections or unresolved interpretation. Consult the review register for the checks and decisions.