bermejo_1977#
D. Bermejo, R. Escribano and J. M. Orza, “Absolute Raman intensities of CH4, CH3D, CH2D2, CHD3, and CD4”, J. Mol. Spectrosc. 65, 345 (1977)
Source record · Catalogue · Review register
DOI: 10.1016/0022-2852(77)90274-0
Source kind: measurement
Recorded technique: Spontaneous vibrational Raman scattering of the gases at room temperature, Ar+ laser at 488.0 nm (0.5 W), 90-degree scattering with the electric vector of the incident light perpendicular to the direction of observation, f/0.95 collection, a Polaroid analyzer and a scrambler, Jarrell-Ash 25-300 spectrophotometer with photon counting; spectral sensitivity from calibrated tungsten and halogen lamps; collection angle and convergence corrections (pp. 347-348). Relative band intensities in a glass cell at about 1.5 atm; every compound referred to the nu1 band of CH4 in a steel cell (five sequences); the absolute nu1 intensity of CH4 measured against the Rayleigh line of CH4 at about 0.1 atm, 20 alternating recordings (pp. 348-349). The alpha^S tensors (derivatives with respect to Mills’s symmetry coordinates) from a weighted least-squares fit to the 36 intensities and depolarization ratios of the five isotopologues, with Mills’s L matrix (p. 352).
Materials in structured entries: CH4
Dataset quantities: polarizability_derivative, raman_scattering_activity, raman_shift
Contents: 9 datasets; 0 formulas.
Curation notes#
Journal pages 345-353 = PDF pages 1-9 (page n of the PDF is p. 344 + n). The citation first requested, ‘J. Raman Spectrosc. 6’, is wrong: the paper is J. Mol. Spectrosc. 65, 345 (1977) (checked against the first page).
SCOPE AND ISOTOPOLOGUES. Only CH4 (12CH4, natural methane, purity >= 99.9 %) is a curated material. The deuterated isotopologues CH3D (~98 %), CH2D2 (~94 %), CHD3 (~85 %) and CD4 (~89 %, with air and CHD3) (p. 347) fill the rest of Tables I and II and are not extracted: for review, CD4 nu1 (2108.6 cm-1) I = 71.9 and 115 +- 8 with 2nu2, nu2 + nu4 and 2nu4 added (Table II); CD4 nu3 (2258.5 cm-1) 70.5 +- 5.
WHAT THE INTENSITY IS. Table I footnote b: ‘I = g_i (45 alpha’^2 + 7 gamma’^2) . N . 10^-32 cm^4 gr^-1 (Where N is the Avogadro Number)’: the scattering activity, as in Murphy et al. 1969 (murphy_1969), so a printed number is in angstrom^4/amu exactly. It is absolute: ‘we measured the absolute intensity of the nu1(a1) band of methane with reference to the Rayleigh line’ of CH4 (p. 348; the reduction from the Rayleigh line, through CH4’s polarizability and anisotropy, is not given), and every other band was referred to CH4’s nu1 (p. 348). ‘We found (45 alpha’^2 + 7 gamma’^2) = 223 . N . 10^-32 g^-1 cm^4; comparable, for instance, with 237 and 223, calculated from data published in Refs. (10) and (11)’ (p. 349): the two reproduced values are the inline dataset intensity_CH4_nu1_others. The excitation wavelength does not enter the activity; it is 488.0 nm (air) for every datum.
TABLE I (p. 348): band positions (‘a: Our measurement’; nu4’s 1310 cm-1 carries no mark and is excluded from shift_CH4), intensities and depolarization ratios. Every CH4 depolarization ratio is ‘d: Expected values, not measured’ (0 for nu1, 3/4 for the others): none is extracted. Footnote c defines rho = 3 gamma’^2/(45 alpha’^2 + 4 gamma’^2), the ratio for linearly polarized incident light. nu4’s intensity is an upper limit, ‘<= 0.05^Q’ (Q branch only), not extracted. No uncertainty is printed in Table I; Table II gives the adopted values with their +-.
TABLE II (p. 350): ‘Observed and Calculated Intensities and Depolarization Ratios’. Footnote a: ‘Intensities of overtones and combinations assumed to be in interaction with fundamentals have been added to that of the fundamental’, so CH4 nu1’s 230 +- 12 is Table I’s 223 + 7 (2nu2); nu2 7.0 +- 0.4 and nu3 128 +- 7 are Table I’s. ‘We have thus adopted as experimental intensities, I_exp, those given in Table II’ (p. 352). The +- level is not stated. I_calc is recomputed from the fitted alpha^S tensors (use = “check”); the fit’s ‘standard deviation of the calculated values of the data is sigma = 0.94’ (p. 352). nu4: calculated 0.22, experimental ‘<= 0.24’ (not extracted).
THE alpha^S INVARIANTS (p. 352): ‘From a weighted least-squares adjustment of the 36 experimental measurements, using the L matrix derived from Mills (6), we find: |c(S1)| = 2.260 +- 0.042 A^2; |c(S2)| = 0.139 +- 0.015 A^2; c(S3) = 1.366 +- 0.077 A^2; c(S4) = 0.00 +- 0.10 A^2 (signs of c(S3) and c(S4) may be simultaneously changed)’: the derivatives of the polarizability tensor with respect to Mills’s symmetry coordinates, the one parameter of each tensor (theory, pp. 345-346: for S1, alpha_xx’ = alpha_yy’ = alpha_zz’ = c, the mean-polarizability derivative; S2, S3, S4 traceless). They are isotope invariant, so they hold for CH4 and every deuterated form. Datasets dS1_CH4 (component mean) and dS_aniso_CH4 (component anisotropy: the tensor element c, not the invariant gamma’). Check (2026-09-26): for CH4, I(nu1) = 45 alpha_1’^2 with alpha_1’ = l_11 c(S1) and l_11 = m_H^(-1/2) (S1 the symmetric sum of the four C-H stretches with coefficient 1/2); 230 gives c(S1) = (230/45)^(1/2) 1.008^(1/2) = 2.270, 223 gives 2.235: the fitted 2.260 lies between (the fit uses all five molecules).
ELECTRO-OPTICAL PARAMETERS (p. 352), from Eqs. (3)-(6) in the first-order bond polarizability approximation: ‘|alpha’_C-H| = 1.130 +- 0.021 A^2; |gamma_C-H| = 0.279 +- 0.030 A^3; |gamma’_C-H| = 2.05 +- 0.16 A^2; |gamma’^(alpha)_C-H| = 0.18 +- 0.13 A^2, which agree fairly well with those found by Yoshino and Bernstein’. Eq. (3): alpha’_C-H = (1/3)|alpha_l’ + 2 alpha_p’| = (1/2)(dalpha/dS1)_xx, the derivative of the mean bond polarizability with respect to the C-H bond length (1.130 = 2.260/2, checked); Eq. (5): gamma’_C-H = |alpha_l’ - alpha_p’| = (3/2)(dalpha/dS3)_yz (1.366 x 3/2 = 2.049, checked). The datasets dalpha_CH_CH4 (component mean) and dgamma_CH_CH4 (component anisotropy) hold them per bond. gamma_C-H (a bond polarizability anisotropy, not per molecule) and gamma’^(alpha) (a derivative with respect to the bond angle; its sign is argued negative, p. 352) have no quantity: notes only. Sign: ‘alpha’_C-H must be positive’ (Yoshino and Bernstein); no reason is found to choose the sign of gamma’_C-H (p. 352).
FOR REVIEW (solprop’s CH4 1.04e-20 m^2, Murphy et al.’s Table I, ref. 17): the same per-bond mean derivative here is 1.130 +- 0.021 A^2 = 1.130e-20 m^2 (8.7 % higher), from a laser measurement against the Rayleigh line; Murphy et al.’s own four values are 1.03 to 1.08.
ISOTOPE RULES (Table III, p. 351, printed as an equation block garbled in the library text): the sum rules hold to 0.96-1.05. Not extracted.
Recorded bibliographic identity status: VALIDATED_WITH_WARNINGS. This concerns identification of the source; it does not establish the scientific correctness of its contents.
Datasets#
bermejo_1977/shift_CH4#
{
"id": "shift_CH4",
"material": "CH4",
"file": "CH4/bermejo_1977__shift_CH4.csv",
"table": "tbl_602282e66a5e",
"quantity": "raman_shift",
"unit": "cm-1",
"abscissa": "label",
"use": "check",
"excluded_rows": {
"nu4 (f2)": "1310 cm-1 is not marked 'a: Our measurement' and its source is not stated"
},
"parameters": {
"transition": "per row: the band of the row label (Raman band maximum)"
}
}
Table I (p. 348), nu/cm-1 of CH4’s bands, measured here (footnote a): band maxima of room-temperature gas spectra, not band origins. nu3 is printed as two braced maxima (3016.7, 3021.3), both kept; 2nu2 is printed ‘~3071’ (approximate).
bermejo_1977/intensity_CH4#
{
"id": "intensity_CH4",
"material": "CH4",
"file": "CH4/bermejo_1977__intensity_CH4.csv",
"table": "tbl_602282e66a5e",
"quantity": "raman_scattering_activity",
"unit": "angstrom4/amu",
"abscissa": "label",
"use": "primary",
"parameters": {
"mode": "per row: nu1 (a1) C-H symmetric stretch, the 2nu2 overtone, nu2 (e), nu3 (f2)"
}
}
Table I (p. 348), I = g(45 alpha’^2 + 7 gamma’^2) in N x 10^-32 cm^4 g^-1 (N Avogadro’s number), exactly angstrom^4/amu; absolute, through CH4’s nu1 against the Rayleigh line of CH4 (p. 348), 488.0 nm. Each band on its own (nu1 without 2nu2). No uncertainty in Table I: Table II’s adopted values carry +- 12 (nu1 with 2nu2), 0.4 (nu2) and 7 (nu3), about 5 %, level not stated.
bermejo_1977/intensity_exp_CH4#
{
"id": "intensity_exp_CH4",
"material": "CH4",
"file": "CH4/bermejo_1977__intensity_exp_CH4.csv",
"table": "tbl_29036d066e28",
"quantity": "raman_scattering_activity",
"unit": "angstrom4/amu",
"abscissa": "label",
"use": "check",
"uncertainty": {
"column": true,
"level": "not stated"
},
"parameters": {
"mode": "per row: nu1 (a1) with 2nu2 added, nu2 (e), nu3 (f2)"
}
}
Table II (p. 350), I_exp: the adopted experimental intensities, the same measurement as Table I (intensity_CH4) regrouped: nu1’s 230 includes the 2nu2 overtone’s 7 (footnote a). The +- (the sigma column) has no stated level.
bermejo_1977/intensity_calc_CH4#
{
"id": "intensity_calc_CH4",
"material": "CH4",
"file": "CH4/bermejo_1977__intensity_calc_CH4.csv",
"table": "tbl_29036d066e28",
"quantity": "raman_scattering_activity",
"unit": "angstrom4/amu",
"abscissa": "label",
"use": "check",
"parameters": {
"mode": "per row: nu1 (a1), nu2 (e), nu3 (f2)"
}
}
Table II (p. 350), I_calc: recomputed from the four fitted alpha^S parameters (a fit to all five isotopologues), to compare with I_exp.
bermejo_1977/intensity_CH4_nu1_others#
{
"id": "intensity_CH4_nu1_others",
"material": "CH4",
"table": "text",
"quantity": "raman_scattering_activity",
"unit": "angstrom4/amu",
"abscissa": "label",
"use": "reproduced",
"reproduced_from": [
"C. M. Penney, L. M. Goldman and M. Lapp, Nature (London) 235, 110 (1972)",
"D. G. Fouche and P. K. Chang, Appl. Phys. Lett. 20, 7 (1972)"
],
"parameters": {
"mode": "nu1 (a1), the C-H symmetric stretch"
}
}
2 inline points in the source record.
p. 349: CH4 nu1’s 223 is ‘comparable, for instance, with 237 and 223, calculated from data published in Refs. (10) and (11)’ (Penney et al.; Fouche and Chang): these authors’ reductions of the cited laser cross sections to the scattering activity (N x 10^-32 cm^4 g^-1 = angstrom^4/amu).
bermejo_1977/dS1_CH4#
{
"id": "dS1_CH4",
"material": "CH4",
"table": "text",
"quantity": "polarizability_derivative",
"unit": "angstrom2",
"abscissa_unit": "nm",
"wavelength_medium": "standard_air",
"use": "primary",
"uncertainty": {
"column": true,
"level": "not stated"
},
"parameters": {
"component": "mean",
"mode": "nu1 (A1): the symmetry coordinate S1 (Mills 1960)",
"coordinate": "S1, Mills's symmetry coordinate (the symmetric sum of the C-H stretches)"
}
}
1 inline points in the source record.
p. 352: |c(S1)| = 2.260 +- 0.042 A^2, the element alpha_xx’ = alpha_yy’ = alpha_zz’ of the derivative of the polarizability tensor (volume, A^3) with respect to Mills’s symmetric-stretch symmetry coordinate S1 (A): the mean-polarizability derivative. Isotope invariant, fitted to the 36 data of the five isotopologues; the sign is not determined by the fit (positive by Yoshino and Bernstein’s argument, p. 352). The +- level is not stated. Excitation 488.0 nm (air).
bermejo_1977/dS_aniso_CH4#
{
"id": "dS_aniso_CH4",
"material": "CH4",
"table": "text",
"quantity": "polarizability_derivative",
"unit": "angstrom2",
"abscissa_unit": "nm",
"wavelength_medium": "standard_air",
"use": "primary",
"uncertainty": {
"column": true,
"level": "not stated"
},
"parameters": {
"component": "anisotropy",
"mode": "per row: S2 (E), S3 and S4 (F2) symmetry coordinates (Mills 1960)",
"coordinate": "the symmetry coordinate of the row (Mills 1960)"
}
}
3 inline points in the source record.
p. 352: |c(S2)| = 0.139 +- 0.015, c(S3) = 1.366 +- 0.077, c(S4) = 0.00 +- 0.10 A^2, the one parameter of each traceless derivative tensor with respect to Mills’s symmetry coordinates S2 (E), S3 and S4 (F2) (the tensor forms, pp. 345-346): anisotropic derivatives, tensor elements rather than the invariant gamma’. ‘Signs of c(S3) and c(S4) may be simultaneously changed’. The +- level is not stated.
bermejo_1977/dalpha_CH_CH4#
{
"id": "dalpha_CH_CH4",
"material": "CH4",
"table": "text",
"quantity": "polarizability_derivative",
"unit": "angstrom2",
"abscissa_unit": "nm",
"wavelength_medium": "standard_air",
"use": "primary",
"uncertainty": {
"column": true,
"level": "not stated"
},
"parameters": {
"component": "mean",
"mode": "nu1 (A1), C-H stretch",
"coordinate": "r_CH, the bond length (per bond)"
}
}
1 inline points in the source record.
p. 352: |alpha’_C-H| = 1.130 +- 0.021 A^2, the derivative of the mean C-H bond polarizability with respect to the bond length, Eq. (3), alpha’_C-H = (1/3)|alpha_l’ + 2 alpha_p’| = (1/2)(dalpha/dS1)_xx (1.130 = 2.260/2). The quantity Murphy et al. tabulate as dalpha/dr (murphy_1969 dadr_CH4_nu1: 1.03-1.08). The +- level is not stated.
bermejo_1977/dgamma_CH_CH4#
{
"id": "dgamma_CH_CH4",
"material": "CH4",
"table": "text",
"quantity": "polarizability_derivative",
"unit": "angstrom2",
"abscissa_unit": "nm",
"wavelength_medium": "standard_air",
"use": "primary",
"uncertainty": {
"column": true,
"level": "not stated"
},
"parameters": {
"component": "anisotropy",
"mode": "C-H stretch (from nu3, F2)",
"coordinate": "r_CH, the bond length (per bond)"
}
}
1 inline points in the source record.
p. 352: |gamma’_C-H| = 2.05 +- 0.16 A^2, the derivative of the C-H bond polarizability anisotropy |alpha_l’ - alpha_p’| with respect to the bond length, Eq. (5) = (3/2)(dalpha/dS3)_yz (1.366 x 1.5 = 2.049). Sign not determined (p. 352). The +- level is not stated.
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.