leveque_1983 ============ G\. Leveque, C\. G\. Olson and D\. W\. Lynch, "Reflectance spectra and dielectric functions for Ag in the region of interband transitions", Phys\. Rev\. B 27, 4654\-4660 \(1983\) `Source record `__ · :doc:`Catalogue ` · :doc:`Review register ` DOI: `10\.1103/PhysRevB\.27\.4654 `__ **Source kind:** measurement **Recorded technique:** Near\-normal\-incidence reflectance of silver, 3\.5\-30 eV, with p\-polarised synchrotron radiation at 10 deg incidence \(Synchrotron Radiation Center, University of Wisconsin\) in the reflectometer of Olson and Lynch \(Phys\. Rev\. B 9, 3159 \(1974\)\), collecting a 6 deg spread of the reflected beam; several detectors, choppers and filters against second order and scattered light, and corrections for scattered radiation afterwards \(the grating 'was not optimal'\)\. Samples \(pp\. 4654\-4655\)\: Ag single crystals polished with Al2O3 abrasives, then chemically polished by alternate immersion in a 1\:1 solution of 50 mol % H2O2 and 0\.42 M NaCN and in 0\.77 M aqueous NaCN, under nitrogen, and loaded under nitrogen; \(100\) and \(111\) faces; Ag films evaporated in situ \(pressure in the 1e\-7 Torr range\) on the chemically polished crystals and on glass\. The spectra were Kramers\-Kronig analysed for epsilon and the loss function, with J\. H\. Weaver's unpublished absorptance A = 1 \- R at 0\.16\-2\.8 eV as the low\-energy extension, Haensel et al\.'s absorption \(Appl\. Opt\. 7, 301 \(1968\)\) to 105 eV and, above 105 eV, Hagemann, Gudat and Kunz's compilation \(DESY report SR\-74/7\) \(p\. 4656\)\. **Materials in structured entries:** Ag **Dataset quantities:** permittivity\_imaginary **Contents:** 1 dataset; 0 formulas. Curation notes -------------- Journal pages 4654\-4660 = PDF pages 1\-7\. Identity checked against the first page \(the library flags warnings on the bibliographic record only\)\. Nothing is tabulated as optical constants\: the reflectance and the dielectric function are in figures, so the record holds one text value \(below\) and notes\. TABLE I \('Reflectances of Ag', p\. 4656, tbl\_dea1c0551bce; image checked\)\: R at 5, 9\.5, 15 and 23 eV of four samples\. Clean crystal 0\.250, 0\.053, 0\.092, 0\.089; film on crystal 0\.228, 0\.053, 0\.080, 0\.074; film on glass 0\.268, 0\.068, 0\.098, 0\.088; 'estimated ideal value \(see text\)' 0\.294, 0\.068, 0\.113, 0\.106\. A reflectance has no quantity\: notes only\. The ideal value is the clean crystal's corrected by the ratio \(film on glass\)/\(film on crystal\) \(p\. 4656\), 'the maximum value of reflectance achievable on Ag, i\.e\., strain free and unoxidized' \(not corrected for submicroscopic roughness\)\. CHECK \(2026\-09\-28\)\: the clean\-crystal value times that ratio gives 0\.2939, 0\.068, 0\.1127 and 0\.1058, the printed ideal values to their rounding\. WHAT THE FIGURES HOLD \(not digitised\)\. Fig\. 1\: R against energy \(to 30 eV\) of the chemically polished crystal \(solid\), the film on glass \(dashed\), the crystal before the chemical etch \(dot\-dashed\), with Irani, Huen and Wooten, Hagemann et al\. \(crosses\), Ehrenreich and Philipp \(dots\) and Table I's ideal values \(circles\)\. Figs\. 2 and 3\: epsilon\_1 and epsilon\_2 \(0\-30 eV\) from the single\-crystal \(solid\) and film \(dashed\) reflectance, with Irani et al\. and Hagemann et al\.; Fig\. 4\: the loss function Im\(\-1/eps\) with Schluter's \(its caption says 'from the dielectric function of Figs\. 5 and 6', presumably Figs\. 2 and 3\); Fig\. 5\: epsilon\_2 \(film\) against Lasser, Smith and Benbow's calculation and Hagemann et al\.; Fig\. 6\: \-d mu/dE and \-d^2 mu/dE^2 against the thermotransmission of Olson, Lynch and Rosei\. Which data set is 'the' result\: 'we feel the best experimental spectra, i\.e\., those most representative of Ag, are probably our film data\. These are what were Kramers\-Kronig analyzed and presented' \(p\. 4658\), yet Figs\. 2 and 3 show both\. UNCERTAINTY AND MAGNITUDE \(p\. 4658\)\: the three crystal faces gave the same spectra 'within experimental errors, about 5% of the measured values' \(p\. 4655 names two faces, \(100\) and \(111\); p\. 4658 says three\)\. The reflectance of strain\-free, atomically clean Ag is higher than measured, 'but not more than 15% higher', which 'will lead to higher values of epsilon\_2'; 'Corrections for surface oxide and strain could raise our epsilon\_2 spectrum, but not more than 15% at any energy'\. Above 10 eV the magnitudes are well below Hagemann et al\.'s compilation, whose absorption at 16\-110 eV the paper judges too high \(pp\. 4657\-4658\)\. TEXT VALUES\. epsilon\_2 at 'the 4\.5\-eV maximum' is 3\.77 \('some authors report epsilon\_2 values at the 4\.5\-eV maximum slightly higher \(up to 4\.1\) than ours \(3\.77\)', Huebner et al\. and Meyer et al\. on quartz; p\. 4656\)\: dataset eps2\_max\_Ag\. Structures\: a new weak peak at 11\.5 eV; 15\.2, 22\.9 and 25\.5 eV refined \(abstract; pp\. 4657\-4658\)\. Table II \(p\. 4658, tbl\_e9c1a6e4ab67; image checked\), 'Optical structures in the \(8\-30\)\-eV range' \(eV\), columns R, epsilon\_2 \(our results\), \-d^2 mu/dE^2, Delta T/T \(Ref\. 21, Olson, Lynch and Rosei\) and the band pairs of Lasser et al\. \(Ref\. 19\)\: a 10\.0, 9\.9, 10\.0, \-, 3,4,5\-\>7; b 11\.4, 11\.4, 11\.3, \-, 5,6\-\>8; c 15\.2, 14\.6, 15\.2, 15\.6, 4,5\-\>9 and 1,2,3\-\>8; d 22\.9, 22\.2, 22\.6, 22\.6, 2,3\-\>8,9 and 3,4,5\-\>10; e 25\.0, \-, 25\.1, 25\.3, 1,2,3\-\>10\. The summary's 25\.5 eV is 25\.0 in Table II's R column \(image checked\)\: a discrepancy between text and table, not resolved here\. Structure energies have no quantity\. THE LOW\-ENERGY PART AND WEAVER'S DATA\. The Kramers\-Kronig analysis used J\. H\. Weaver's unpublished absorptance \(Ref\. 4, 'private communication'\) at 0\.16\-2\.8 eV; 'From 1\.8 to 3\.8 eV our epsilon\_2 curve, calculated from Weaver's \(1\-R\) data, is lower and flatter than most of the literature values\. This difference is due, in part, to the low temperature at which these data were taken' \(p\. 4657\), comparable only with Johnson and Christy's films on quartz \(the paper's Ref\. 18 is printed 'Phys\. Rev\. B 11, 1315 \(1975\)'; the silver data on quartz are johnson\_1972, Phys\. Rev\. B 6, 4370\: the reference may point to the wrong paper; the 1975 paper is not in the library\)\. BABAR AND WEAVER \(babar\_2015\) 'used the results of Leveque, Olson, and Lynch up to 30 eV' to extend silver's range for their Kramers\-Kronig analysis \(Babar and Weaver, p\. 477\)\. They do not say which of these reflectances \(film, crystal or ideal\) they took; this paper publishes the reflectance only as the curves of Fig\. 1 and the four energies of Table I, so their numbers came from elsewhere \(not in the library\)\. Note the circularity\: this paper's own analysis rests below 2\.8 eV on Weaver's absorptance, and Babar and Weaver's silver above 6 eV on this paper's reflectance\. REFERENCE 1 is Hagemann, Gudat and Kunz, DESY report SR\-74/7 \(1974\), 'see also J\. Opt\. Soc\. Am\. 65, 742 \(1975\)' \(hagemann\_1975\)\. **Recorded bibliographic identity status:** VALIDATED\_WITH\_WARNINGS. This concerns identification of the source; it does not establish the scientific correctness of its contents. Datasets -------- leveque\_1983/eps2\_max\_Ag ~~~~~~~~~~~~~~~~~~~~~~~~~~~ .. code-block:: text { "id": "eps2_max_Ag", "material": "Ag", "table": "text", "quantity": "permittivity_imaginary", "abscissa_unit": "eV", "use": "check", "parameters": { "technique": "Kramers-Kronig analysis of synchrotron reflectance (3.5-30 eV)" } } 1 inline points in the source record. Text, p\. 4656\: epsilon\_2 of silver at 'the 4\.5\-eV maximum' is 3\.77 \(Kramers\-Kronig analysis of this paper's reflectance with Weaver's absorptance below 2\.8 eV; which sample, film or crystal, is not said\)\. The energy is the paper's round label of the maximum, not a measured abscissa\: a check on the height of silver's interband maximum near 4\.5 eV, not a point to fit\. \(Johnson and Christy's Table I gives 2nk = 3\.75 at 4\.49 eV and 3\.79 at 4\.61 eV\.\) 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 :doc:`review register ` for the checks and decisions.