Martin J. Reisfeld

The electronic spectrum of cesium hexafluoromanganese(IV)

Abstract A number of high purity samples of Cs 2 MnF 6 have been prepared and their electronic spectra studied, both in absorption and emission. The observed peaks were assigned to the crystalfield energy levels for an octahedral d 3 configuration. A large number of vibronic components have been observed and correlated with data on the ground state vibrational frequencies. Evidence of spin-orbit splitting of several of the bands was adduced. Recent work on the MnF 6 2− complex was examined and some of the discrepancies discussed. The crystal-field parameters have been derived, and a value for the optical electronegativity of Mn(IV) calculated. The results are: D q = 2180 cm −1 , B = 650 cm −1 , C = 3972 cm −1 , and χ opt = 2.90. The nephelauxetic ratios are β 55 = β 35 = 0.61.

Infrared spectrum and potential constants of silicon tetrafluoride

Doppler‐limited tunable diode laser spectra of ν4 of 28SiF4 have been analyzed and the spectroscopic constants determined. In contrast to most earlier low‐resolution studies, the Coriolis constant ζ4, when combined with ζ3 as obtained from previous laser spectroscopy, yields a zeta sum that is within 5% of the expected harmonic value of 1/2. The band origins of 12 overtones and combinations have been obtained from Fourier‐transform spectra (0.04 cm−1 resolution), resulting in estimates of the anharmonicity constants and harmonic frequencies. From the Coriolis constants and the isotope shifts in ν3 we have redetermined the general quadratic force field of SiF4.

High-resolution spectroscopy of the 16-μm bending fundamental of CF4

Abstract The 16-μm bending fundamentals ( ν 4 ) of 12 CF 4 , 13 CF 4 , and 14 CF 4 have been observed at Doppler-limited resolution using a tunable PbSnSe semiconductor diode laser. The tetrahedral splittings of the rotational manifolds have been observed in all three branches, and in particular the dense and partially overlapping transitions in the Q branches have been resolved and assigned. A least-squares fit of the Hamiltonian, including off-diagonal terms, yielded five scalar and three tensor spectroscopic constants for each of the three isotopes. From these constants the upper-state rotational constant B 4 and the Coriolis constant ζ 4 have been calculated, together with some of the other molecular constants. An absorption feature at about 0.18 cm −1 to the red of the main Q branch of each isotopic species has been identified as the Q branch of ( ν 2 + ν 4 ) − ν 2 , which is the transition that lases when CF 4 is pumped by a CO 2 laser at 9.4 μm (i.e., in ν 2 + ν 4 ).

Prediction and Interpretation of Free‐Ion and Crystal‐Field Spectra of the Actinides. The Intermediate Crystal‐Field Diagram for 5f2 Np5+ in Octahedral CsNpF6

The problem of identification and characterization of the many oxidation states of the actinide elements which give rise to f–f electronic spectra is treated both for free‐ion and crystal‐field spectra. For the free‐ion, nonrelativistic self‐consistent‐field calculations on fn configurations of the actinides have yielded values for the Coulomb and spin–orbit interaction parameters from which electronic spectra may be predicted. Comparison of these calculated energy levels with the spectra observed for several actinides has been made. Crystal‐field splitting of the free‐ion levels was examined in detail for the case of 5f2Np5+ in CsNpF6. A complete intermediate crystal‐field coupling diagram for this f2 configuration ion under Oh point‐group symmetry was constructed and the observed spectrum was fit to the diagram confirming the predominant octahedral structure of NpF6−. The combined Coulomb, spin–orbit, and octahedral crystal‐field spectroscopic parameters for NpF6− were: E1 = 3144, E2 = 16.75, E3 = 251.9...

The ν 2 band of N 2 O as a frequency standard in the17-μm region of the infrared

Direct measurements of the absorption spectra of N/sub 2/O were made in order to determine if higher order terms are needed before the ..nu../sub 2/ band can serve as a frequency standard.(AIP)

Electronic Spectra of the 5f3 Actinides: U3+, Np4+, Pu5+, and AmO2++. The f3 Intermediate Coupling Diagram

The absorption spectra of fluoride salts of 5f3Np4+ obtained at room temperature in various environments were compared with the known spectra of f3Nd3+ and U3+. Correlation with known spectra allowed assignment of levels to Np4+, and based on these, the complete 41‐level f3 intermediate spin–orbit coupling diagram was constructed. The diagram was used to interpret the absorption spectra and to make spectroscopic assignments to 12 low‐lying electronic energy levels for Pu5+. Ten low‐lying levels for Am(VI) obtained from published AmO2++ aqueous solution spectra were interpreted also. Spectroscopic parameters obtained from least‐squares fits to the observed spectra were: Np4+, F2 = 232.4 cm−1, ζ = 2178 cm−1; Pu5+, F2 = 230.5 cm−1, ζ = 2295 cm−1; AmO2++, F2 = 260.3 cm−1, ζ = 3070 cm−1. Only the lowest‐lying energy levels were found to be in substantial agreement with the f3 intermediate coupling diagram.

Spectroscopy of 12 CF 4 features near the 9-μm 12 C 16 O 2 R(10), R(12), and R(18) lines by CO 2 -laser and diode-laser spectroscopy

The (12)CF(4) molecule has been made to lase at various wavelengths in the 16-microm v(4) + V(2) ? V(2) band by pumping in the 9-microm 0 ? V(2) + V(4) band with (12)C(16)O(2) lines. The strongest reported (12)CF(4) laser line occurs at 615.06 cm(-1) and is pumped by 9R12 [9-microm band, R(12) line]. We have measured, by two techniques, the absorption of (12)CF(4) in 9R12, and also in 9R10 and 9R18, which are known to result in weak 16-microm laser transitions. This was done both at room temperature and at an estimated 100 K, and striking changes in spectral features were noted as the temperature was lowered. For the 9R12 laser line, we find a (12)CF(4) feature located 30 +/- 3 MHz to the high-frequency side of line center, with a peak absorption coefficient of 5 x 10(-4) to 9 x 10(-4) cm(-1) Torr(-1), depending on temperature. By contrast, there are only weak (12)CF(4) features within +/-40 MHz of the 9R10 and 9R18 laser-line centers, and the absorption coefficients of those features are 1 x 10(-4) to 2 x 10(-4) cm(-1) Torr(-1).

High-resolution Q-branch spectra of the ν2 + ν7 bands of C3O2 in the 12 u̧m region

Tunable diode laser spectra are obtained of several Q branches in the ν2 + ν7 sum bands of 12C316O2 at 820–850 cm−1. Molecular constants are determined for the ground-state transition at 819.69 cm−1 and for the first two hot bands, which are shifted to higher frequency. The l-doubling constant in the ν71 state was found to be 4.16 ± 0.06 × 10−4 cm−1, and that in the ν2 + ν71 state 2.96 ± 0.04 × 10−4 cm−1.

The absorption spectrum of potassium hexafluoronickelate(IV): Infrared and Raman spectra

Abstract The infrared and Raman spectra of solid K 2 NiF 6 was studied. All the active frequencies ν 1 , ν 2 , ν 3 , ν 4 , and ν 5 belonging to the isolated ion point group ( O h ) were ascertained. Several lattice modes were also found in the Raman spectrum. Force constant calculations were carried out for both the general quadratic potential function and the Urey-Bradley potential and the results are compared with those for a similar tetravalent hexafluoro complex K 2 PtF 6 .

Infrared spectrum and normal coordinate analysis of permanganyl fluoride MnO3F

Abstract This paper presents the infrared spectrum of gaseous MnO 3 F from 100 to 4000 cm −1 . A vibrational analysis is made on the basis of C 3 v symmetry and valence force constants are determined. The fundamental frequencies of MnO 3 F are: A 1 = 905.2, 720.7, 337.7, E = 952.5, 373.9 and 264.3 cm −1 . From the band contours and the zeta sum rule, values for the Coriolis coupling constants are evaluated. The values are: ζ 4 = 0.10, ζ 5 = −0.03, ζ 6 = 0.37. Thermodynamic properties are presented over the temperature range 235–1000°K.