donley_1993#
E. A. Donley and D. P. Shelton, Chem. Phys. Lett. 215, 156 (1993)
Source record · Catalogue · Review register
DOI: 10.1016/0009-2614(93)89280-u
Source kind: measurement
Recorded technique: ESHG with periodic phase matching (argon-ion laser, 514.5 nm, nu = 19430 cm^-1), as in shelton_1990; four electrode arrays of different periods (Table 1: L = 5.080, 2.692, 2.032, 1.270 mm; N = 82, 150, 200, 160 pairs) give four phase-match densities (rho(H2) = 80.5-323.5 mol m^-3); about 200 measurement triplets; 99.999 % gases at 1-8 atm and 298 K (He 25-125 atm); densities by the virial equation of state; optical field parallel to the static field (pp. 1-3).
Materials in structured entries: Ar, H2, He, N2
Dataset quantities: hyperpolarizability, hyperpolarizability_ratio, phase_match_density_ratio
Contents: 19 datasets; 0 formulas.
Curation notes#
Hyperpolarizability ratios of H2/He, Ar/H2 and N2/H2 as functions of gas density, ‘with 0.1% accuracy’: the zero-density intercepts are the isolated-molecule ratios, and the slopes measure the pair (collision) contribution to gamma (the density correction to ESHG gamma). Referred to by Shelton & Rice 1994 as ref 35 (‘these effects are at the 0.1% level in the measurements for H2’).
Definitions: gamma_A/gamma_B = (S^(1/2)/q rho V)_A / (S^(1/2)/q rho V)_B (Eq. 1, p. 2), S the harmonic photon flux, rho the phase-match density, V the electrode voltage, and q = (T_1^2 T_2)^(1/2) (F)^(1/2) (n_omega^(zeta-2) n_2omega^-1)^(1/2) (f_0 f_omega^2 f_2omega) (Eq. 2): window transmission, the pressure-induced lens of the entrance window, refractive-index factors (zeta ~ 0.4) and the Lorentz local-field factors f = (n^2 + 2)/3. ‘The largest correction to gamma is -0.8% for He gas with array No. 4’ and ‘the net correction to gamma_A/gamma_B is typically much less than 0.1%’ (p. 3). gamma is the ESHG gamma of shelton_1990 (Taylor convention; 1 au = 6.235377e-65 C^4 m^4 J^-3, Table 3 note a). Uncertainty: ‘Statistical and calibration uncertainties each contribute about +-0.07% to the error bars on the final results. The stated uncertainties are treated as one standard deviation. The final results may be somewhat more accurate than the assigned error bars suggest’ (p. 2). Parts: the molecular ratios are of the total ESHG gamma (the ab initio comparison adds gamma^v and gamma^R for H2, Table 3 note b).
PAIR (DENSITY) CORRECTIONS, not expressible as a dataset (no quantity for a hyperpolarizability density coefficient): gamma_A/gamma_B = (gamma_A/gamma_B)_0 [1 + b(AB) rho(H2)] (Eq. 5), b(AB) = (b_A - b_B rho_B/rho_A)(rho_A/rho_C), C = H2 (Eq. 6). Table 3, measured b(AB) in 10^-6 m^3 mol^-1: H2/He +5.6 +- 6.2, Ar/H2 -7.0 +- 5.0, N2/H2 -6.9 +- 4.6; calculated (binary dipole-induced-dipole model) -2.1, +4.5, +3.4: ‘The measured and calculated slopes agree in magnitude, but they are of opposite sign’ (p. 6). DID model: gamma(R) = gamma [1 + 48 (alpha/4 pi eps0 R^3)^2] (Eq. 3), gamma(rho) = gamma (1 + b rho) (Eq. 4). Table 4 (Lennard-Jones 6-12 potential): He, H2, Ar, N2: alpha (10^-40 C^2 m^2 J^-1, at 632.8 nm, from Bogaard & Orr 1975) 0.230, 0.92, 1.85, 1.97; sigma (nm) 0.257, 0.30, 0.343, 0.366; eps/k (K) 11, 40, 122, 97 (Reed & Gubbins 1973); (Delta gamma/gamma)_{R = sigma} 0.00714, 0.0449, 0.0815, 0.0629; b (10^-6 m^3 mol^-1) 0.46, 4.59, 12.43, 11.67; and the local-field coefficient c = d(f_0 f_omega^2 f_2omega)/d rho = 2.10, 8.52, 17.13, 18.15 (10^-6 m^3 mol^-1). ‘Extrapolated to liquid density, the binary DID contribution in eq. (4) is 1%, 16%, 34% or 43% of the individual molecule contribution for He, H2, N2 or Ar’ (p. 6); the measured slopes suggest an electron-overlap contribution of about -2 x DID (p. 6). The Table 4 polarizabilities are reproduced (Bogaard & Orr) and not extracted.
Table 1 (array parameters and typical H2 signals) is recorded in the technique only. The library’s validation notes ‘REFERENCES_REORDERED’ on p. 7 (a stray Leonard 1974 reference line before [1]); the references used here are unaffected. The table cells agree with the images.
Recorded bibliographic identity status: VALIDATED_WITH_WARNINGS. This concerns identification of the source; it does not establish the scientific correctness of its contents.
Datasets#
donley_1993/gamma_H2_over_He_arrays#
{
"id": "gamma_H2_over_He_arrays",
"material": "H2",
"file": "H2/donley_1993__gamma_H2_over_He_arrays.csv",
"table": "tbl_6498821f87d2",
"quantity": "hyperpolarizability_ratio",
"unit": "1",
"abscissa_unit": "cm-1",
"use": "check",
"uncertainty": {
"column": true,
"level": "1 sigma"
},
"parameters": {
"reference_material": "He",
"process": "eshg",
"convention": "T",
"part": "total",
"temperature_k": 298.0
}
}
Table 2 (p. 3): gamma_A/gamma_B with A = H2, B = He, as printed, one row per electrode array (per phase-match density; Table 1 gives rho(H2) = 80.5, 152.4, 202.3, 323.5 mol m^-3; the other gases are at nearly fixed density ratios, Table 2). Gas pressures 1-8 atm at T = 298 K (He 25-125 atm). ‘The stated uncertainties are treated as one standard deviation’ (p. 2). Finite-density values: the zero-density intercept (gamma_H2_over_He_zero_density) is the isolated-molecule result.
donley_1993/gamma_Ar_over_H2_arrays#
{
"id": "gamma_Ar_over_H2_arrays",
"material": "Ar",
"file": "Ar/donley_1993__gamma_Ar_over_H2_arrays.csv",
"table": "tbl_6498821f87d2",
"quantity": "hyperpolarizability_ratio",
"unit": "1",
"abscissa_unit": "cm-1",
"use": "check",
"uncertainty": {
"column": true,
"level": "1 sigma"
},
"parameters": {
"reference_material": "H2",
"process": "eshg",
"convention": "T",
"part": "total",
"temperature_k": 298.0
}
}
Table 2 (p. 3): gamma_A/gamma_B with A = Ar, B = H2, as printed, one row per electrode array (per phase-match density; Table 1 gives rho(H2) = 80.5, 152.4, 202.3, 323.5 mol m^-3; the other gases are at nearly fixed density ratios, Table 2). Gas pressures 1-8 atm at T = 298 K (He 25-125 atm). ‘The stated uncertainties are treated as one standard deviation’ (p. 2). Finite-density values: the zero-density intercept (gamma_Ar_over_H2_zero_density) is the isolated-molecule result.
donley_1993/gamma_N2_over_H2_arrays#
{
"id": "gamma_N2_over_H2_arrays",
"material": "N2",
"file": "N2/donley_1993__gamma_N2_over_H2_arrays.csv",
"table": "tbl_6498821f87d2",
"quantity": "hyperpolarizability_ratio",
"unit": "1",
"abscissa_unit": "cm-1",
"use": "check",
"uncertainty": {
"column": true,
"level": "1 sigma"
},
"parameters": {
"reference_material": "H2",
"process": "eshg",
"convention": "T",
"part": "total",
"temperature_k": 298.0
}
}
Table 2 (p. 3): gamma_A/gamma_B with A = N2, B = H2, as printed, one row per electrode array (per phase-match density; Table 1 gives rho(H2) = 80.5, 152.4, 202.3, 323.5 mol m^-3; the other gases are at nearly fixed density ratios, Table 2). Gas pressures 1-8 atm at T = 298 K (He 25-125 atm). ‘The stated uncertainties are treated as one standard deviation’ (p. 2). Finite-density values: the zero-density intercept (gamma_N2_over_H2_zero_density) is the isolated-molecule result.
donley_1993/density_He_over_H2#
{
"id": "density_He_over_H2",
"material": "He",
"file": "He/donley_1993__density_He_over_H2.csv",
"table": "tbl_6498821f87d2",
"quantity": "phase_match_density_ratio",
"unit": "1",
"abscissa_unit": "cm-1",
"density": "real",
"use": "primary",
"uncertainty": {
"column": true,
"level": "1 sigma"
},
"parameters": {
"reference_material": "H2",
"harmonic": 2,
"process": "ESHG (electric-field-induced second-harmonic generation), periodic phase matching",
"definition": "rho_gas / rho_reference_gas at equal wave-vector mismatch |Delta k| = (4 pi / lambda) |n(2w) - n(w)|; to first order in density = [alpha_ref(2w) - alpha_ref(w)] / [alpha_gas(2w) - alpha_gas(w)]; lambda = fundamental",
"sample_gas": "H2",
"shelton_reference_gas": "He",
"temperature_k": 298.0
}
}
Table 2 (p. 3): rho_B/rho_A with A = H2 (sample), B = He (reference) as printed, filed under He with reference_material H2 so that the printed number is rho_gas/rho_reference (as in shelton_1990). One row per array. Densities from pressure (+-0.02-0.08 %) and temperature (+-0.1 C) with the virial equation of state (p. 2). Caption: ‘The phase match density of the gas is inversely proportional to the polarizability dispersion [alpha(2 omega) - alpha(omega)] ... The measured phase match density ratios show no significant density dependence (an increase by 0.01%-0.02% over this density range is predicted from measured refractive index virial coefficients [4])’.
donley_1993/density_H2_over_Ar#
{
"id": "density_H2_over_Ar",
"material": "H2",
"file": "H2/donley_1993__density_H2_over_Ar.csv",
"table": "tbl_6498821f87d2",
"quantity": "phase_match_density_ratio",
"unit": "1",
"abscissa_unit": "cm-1",
"density": "real",
"use": "primary",
"uncertainty": {
"column": true,
"level": "1 sigma"
},
"parameters": {
"reference_material": "Ar",
"harmonic": 2,
"process": "ESHG (electric-field-induced second-harmonic generation), periodic phase matching",
"definition": "rho_gas / rho_reference_gas at equal wave-vector mismatch |Delta k| = (4 pi / lambda) |n(2w) - n(w)|; to first order in density = [alpha_ref(2w) - alpha_ref(w)] / [alpha_gas(2w) - alpha_gas(w)]; lambda = fundamental",
"sample_gas": "Ar",
"shelton_reference_gas": "H2",
"temperature_k": 298.0
}
}
Table 2 (p. 3): rho_B/rho_A with A = Ar (sample), B = H2 (reference) as printed, filed under H2 with reference_material Ar so that the printed number is rho_gas/rho_reference (as in shelton_1990). One row per array. Densities from pressure (+-0.02-0.08 %) and temperature (+-0.1 C) with the virial equation of state (p. 2). Caption: ‘The phase match density of the gas is inversely proportional to the polarizability dispersion [alpha(2 omega) - alpha(omega)] ... The measured phase match density ratios show no significant density dependence (an increase by 0.01%-0.02% over this density range is predicted from measured refractive index virial coefficients [4])’.
donley_1993/density_H2_over_N2#
{
"id": "density_H2_over_N2",
"material": "H2",
"file": "H2/donley_1993__density_H2_over_N2.csv",
"table": "tbl_6498821f87d2",
"quantity": "phase_match_density_ratio",
"unit": "1",
"abscissa_unit": "cm-1",
"density": "real",
"use": "primary",
"uncertainty": {
"column": true,
"level": "1 sigma"
},
"parameters": {
"reference_material": "N2",
"harmonic": 2,
"process": "ESHG (electric-field-induced second-harmonic generation), periodic phase matching",
"definition": "rho_gas / rho_reference_gas at equal wave-vector mismatch |Delta k| = (4 pi / lambda) |n(2w) - n(w)|; to first order in density = [alpha_ref(2w) - alpha_ref(w)] / [alpha_gas(2w) - alpha_gas(w)]; lambda = fundamental",
"sample_gas": "N2",
"shelton_reference_gas": "H2",
"temperature_k": 298.0
}
}
Table 2 (p. 3): rho_B/rho_A with A = N2 (sample), B = H2 (reference) as printed, filed under H2 with reference_material N2 so that the printed number is rho_gas/rho_reference (as in shelton_1990). One row per array. Densities from pressure (+-0.02-0.08 %) and temperature (+-0.1 C) with the virial equation of state (p. 2). Caption: ‘The phase match density of the gas is inversely proportional to the polarizability dispersion [alpha(2 omega) - alpha(omega)] ... The measured phase match density ratios show no significant density dependence (an increase by 0.01%-0.02% over this density range is predicted from measured refractive index virial coefficients [4])’.
donley_1993/gamma_H2_over_He_zero_density#
{
"id": "gamma_H2_over_He_zero_density",
"material": "H2",
"file": "H2/donley_1993__gamma_H2_over_He_zero_density.csv",
"table": "tbl_d50d62a52000",
"quantity": "hyperpolarizability_ratio",
"unit": "1",
"abscissa_unit": "cm-1",
"use": "primary",
"uncertainty": {
"column": true,
"level": "1 sigma"
},
"parameters": {
"reference_material": "He",
"process": "eshg",
"convention": "T",
"part": "total"
}
}
Table 3 (p. 5): (gamma_A/gamma_B)_0,exp, the zero-density intercept of the weighted least-squares fit gamma_A/gamma_B = (gamma_A/gamma_B)_0 [1 + b(AB) rho(H2)] (Eq. 5) to Table 2. The isolated-molecule ratio; abstract: 19.55 +- 0.03, 1.668 +- 0.002, 1.283 +- 0.001. ‘The present results agree with the best previous experimental results at this wavelength to within 0.5% [6 = shelton_1990]’ (p. 3).
donley_1993/gamma_Ar_over_H2_zero_density#
{
"id": "gamma_Ar_over_H2_zero_density",
"material": "Ar",
"file": "Ar/donley_1993__gamma_Ar_over_H2_zero_density.csv",
"table": "tbl_d50d62a52000",
"quantity": "hyperpolarizability_ratio",
"unit": "1",
"abscissa_unit": "cm-1",
"use": "primary",
"uncertainty": {
"column": true,
"level": "1 sigma"
},
"parameters": {
"reference_material": "H2",
"process": "eshg",
"convention": "T",
"part": "total"
}
}
Table 3 (p. 5): (gamma_A/gamma_B)_0,exp, the zero-density intercept of the weighted least-squares fit gamma_A/gamma_B = (gamma_A/gamma_B)_0 [1 + b(AB) rho(H2)] (Eq. 5) to Table 2. The isolated-molecule ratio; abstract: 19.55 +- 0.03, 1.668 +- 0.002, 1.283 +- 0.001. ‘The present results agree with the best previous experimental results at this wavelength to within 0.5% [6 = shelton_1990]’ (p. 3).
donley_1993/gamma_N2_over_H2_zero_density#
{
"id": "gamma_N2_over_H2_zero_density",
"material": "N2",
"file": "N2/donley_1993__gamma_N2_over_H2_zero_density.csv",
"table": "tbl_d50d62a52000",
"quantity": "hyperpolarizability_ratio",
"unit": "1",
"abscissa_unit": "cm-1",
"use": "primary",
"uncertainty": {
"column": true,
"level": "1 sigma"
},
"parameters": {
"reference_material": "H2",
"process": "eshg",
"convention": "T",
"part": "total"
}
}
Table 3 (p. 5): (gamma_A/gamma_B)_0,exp, the zero-density intercept of the weighted least-squares fit gamma_A/gamma_B = (gamma_A/gamma_B)_0 [1 + b(AB) rho(H2)] (Eq. 5) to Table 2. The isolated-molecule ratio; abstract: 19.55 +- 0.03, 1.668 +- 0.002, 1.283 +- 0.001. ‘The present results agree with the best previous experimental results at this wavelength to within 0.5% [6 = shelton_1990]’ (p. 3).
donley_1993/gamma_H2_over_He_calc#
{
"id": "gamma_H2_over_He_calc",
"material": "H2",
"file": "H2/donley_1993__gamma_H2_over_He_calc.csv",
"table": "tbl_d50d62a52000",
"quantity": "hyperpolarizability_ratio",
"unit": "1",
"abscissa_unit": "cm-1",
"use": "reproduced",
"reproduced_from": [
"bishop_1989",
"bishop_1991"
],
"uncertainty": {
"level": "not stated"
},
"parameters": {
"reference_material": "He",
"process": "eshg",
"convention": "T",
"part": "total"
}
}
Table 3 (p. 5): (gamma_A/gamma_B)_0,calc, ‘obtained using the results of ab initio calculations of gamma for ESHG at nu = 19430 cm^-1’; notes a, b: gamma(He) = 47.946 au (bishop_1989, with the reduced-mass correction), gamma(H2) = gamma^evR = 937.3 au (see H2_calc_components): 937.3/47.946 = 19.549. ‘the current best ab initio results [12-17] are within 0.0%, +2.5% and +3.1% of the present experimental results’ (p. 4).
donley_1993/gamma_Ar_over_H2_calc#
{
"id": "gamma_Ar_over_H2_calc",
"material": "Ar",
"file": "Ar/donley_1993__gamma_Ar_over_H2_calc.csv",
"table": "tbl_d50d62a52000",
"quantity": "hyperpolarizability_ratio",
"unit": "1",
"abscissa_unit": "cm-1",
"use": "reproduced",
"reproduced_from": [
"rice_1992",
"rice_1991",
"bishop_1991"
],
"uncertainty": {
"level": "not stated"
},
"parameters": {
"reference_material": "H2",
"process": "eshg",
"convention": "T",
"part": "total"
}
}
Table 3 (p. 5): (gamma_A/gamma_B)_0,calc, ‘obtained using the results of ab initio calculations of gamma for ESHG at nu = 19430 cm^-1’; notes b, c: gamma(Ar) = 1604 au ‘from CCSD(T) static result and MP2 dispersion curve [16]’ (rice_1992, rice_1991) over gamma(H2) = 937.3: 1604/937.3 = 1.7113. ‘the current best ab initio results [12-17] are within 0.0%, +2.5% and +3.1% of the present experimental results’ (p. 4).
donley_1993/gamma_N2_over_H2_calc#
{
"id": "gamma_N2_over_H2_calc",
"material": "N2",
"file": "N2/donley_1993__gamma_N2_over_H2_calc.csv",
"table": "tbl_d50d62a52000",
"quantity": "hyperpolarizability_ratio",
"unit": "1",
"abscissa_unit": "cm-1",
"use": "reproduced",
"reproduced_from": [
"sekino_1993",
"bishop_1991"
],
"uncertainty": {
"level": "not stated"
},
"parameters": {
"reference_material": "H2",
"process": "eshg",
"convention": "T",
"part": "total"
}
}
Table 3 (p. 5): (gamma_A/gamma_B)_0,calc, ‘obtained using the results of ab initio calculations of gamma for ESHG at nu = 19430 cm^-1’; notes b, d: gamma(N2) = 1241 au ‘from CCSD(T) static result and SCF dispersion curve [17]’ (sekino_1993) over 937.3: 1241/937.3 = 1.3240. ‘the current best ab initio results [12-17] are within 0.0%, +2.5% and +3.1% of the present experimental results’ (p. 4).
donley_1993/He_calc#
{
"id": "He_calc",
"material": "He",
"table": "text",
"quantity": "hyperpolarizability",
"unit": "au",
"abscissa_unit": "cm-1",
"use": "reproduced",
"reproduced_from": [
"bishop_1989"
],
"uncertainty": {
"level": "not stated"
},
"parameters": {
"process": "eshg",
"convention": "T",
"part": "electronic"
}
}
1 inline points in the source record.
Table 3 note a (p. 5): ‘gamma(He) = 47.946 atomic units (1 au = 6.235377e-65 C^4 m^4 J^-3) includes explicit reduced mass correction [12]’, ESHG at 19430 cm^-1 (514.5 nm).
donley_1993/H2_calc_electronic#
{
"id": "H2_calc_electronic",
"material": "H2",
"table": "text",
"quantity": "hyperpolarizability",
"unit": "au",
"abscissa_unit": "cm-1",
"use": "reproduced",
"reproduced_from": [
"bishop_1991"
],
"uncertainty": {
"level": "not stated"
},
"parameters": {
"process": "eshg",
"convention": "T",
"part": "electronic"
}
}
1 inline points in the source record.
Table 3 note b (p. 5): gamma^e(H2) = 945.4 au [13 = bishop_1991], ESHG at 514.5 nm.
donley_1993/H2_calc_total#
{
"id": "H2_calc_total",
"material": "H2",
"table": "text",
"quantity": "hyperpolarizability",
"unit": "au",
"abscissa_unit": "cm-1",
"use": "check",
"uncertainty": {
"level": "not stated"
},
"parameters": {
"process": "eshg",
"convention": "T",
"part": "total"
}
}
1 inline points in the source record.
Table 3 note b (p. 5): ‘gamma(H2) = gamma^evR = 937.3 au from gamma^e(H2) = 945.4 au [13], gamma^v(H2) = -7.43 - 0.13 = -7.56 au (fundamental + overtones), and gamma^R = -0.38 au (quantum expressions for gamma^vR given by eqs. 9-11 of ref. [6], evaluated using J-dependent Raman polarizability matrix elements [14] scaled to lambda = 514.5 nm [15])’. The authors’ sum (945.4 - 7.56 - 0.38 = 937.46, printed 937.3: the sum is 0.16 au off; not explained), the denominator of the calculated ratios.
donley_1993/H2_calc_vibrational#
{
"id": "H2_calc_vibrational",
"material": "H2",
"table": "text",
"quantity": "hyperpolarizability",
"unit": "au",
"abscissa_unit": "cm-1",
"use": "primary",
"uncertainty": {
"level": "not stated"
},
"parameters": {
"process": "eshg",
"convention": "T",
"part": "vibrational"
}
}
3 inline points in the source record.
Table 3 note b (p. 5): gamma^v(H2) = -7.43 - 0.13 = -7.56 au (fundamental + overtones) for ESHG at 514.5 nm, the authors’ evaluation of Eqs 9-11 of shelton_1990 with J-dependent Raman matrix elements (LeRoy & Schwartz 1987) scaled to 514.5 nm (Bishop & Cheung 1980). T not stated (298 K in the experiment).
donley_1993/H2_calc_rotational#
{
"id": "H2_calc_rotational",
"material": "H2",
"table": "text",
"quantity": "hyperpolarizability",
"unit": "au",
"abscissa_unit": "cm-1",
"use": "primary",
"uncertainty": {
"level": "not stated"
},
"parameters": {
"process": "eshg",
"convention": "T",
"part": "rotational"
}
}
1 inline points in the source record.
Table 3 note b (p. 5): gamma^R(H2) = -0.38 au for ESHG at 514.5 nm (the authors’ quantum evaluation, as for H2_calc_vibrational).
donley_1993/Ar_calc#
{
"id": "Ar_calc",
"material": "Ar",
"table": "text",
"quantity": "hyperpolarizability",
"unit": "au",
"abscissa_unit": "cm-1",
"use": "reproduced",
"reproduced_from": [
"rice_1992",
"rice_1991"
],
"uncertainty": {
"level": "not stated"
},
"parameters": {
"process": "eshg",
"convention": "T",
"part": "electronic"
}
}
1 inline points in the source record.
Table 3 note c (p. 5): ‘gamma(Ar) = 1604 au from CCSD(T) static result and MP2 dispersion curve [16]’ (Rice 1992; Rice et al. 1991), ESHG at 514.5 nm.
donley_1993/N2_calc#
{
"id": "N2_calc",
"material": "N2",
"table": "text",
"quantity": "hyperpolarizability",
"unit": "au",
"abscissa_unit": "cm-1",
"use": "reproduced",
"reproduced_from": [
"sekino_1993"
],
"uncertainty": {
"level": "not stated"
},
"parameters": {
"process": "eshg",
"convention": "T",
"part": "electronic"
}
}
1 inline points in the source record.
Table 3 note d (p. 5): ‘gamma(N2) = 1241 au from CCSD(T) static result and SCF dispersion curve [17]’ (sekino_1993), ESHG at 514.5 nm; electronic only.
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.