Arthur G. Maki

Molecular structures of gas‐phase polyatomic molecules determined by spectroscopic methods

Spectroscopic data related to the structures of polyatomic molecules in the gas phase have been reviewed, critically evaluated, and compiled. All reported bond distances and angles have been classified as equilibrium (re), average (rz), substitution (rs), or effective (ro) parameters, and have been given a quality rating which is a measure of the parameter uncertainty. The surveyed literature includes work from all of the areas of gas‐phase spectroscopy from which precise quantitative structural information can be derived. Introductory material includes definitions of the various types of parameters and a description of the evaluation procedure.

Microwave Spectra of Molecules of Astrophysical Interest VI. Carbonyl Sulfide and Hydrogen Cyanide

All available data on the microwave spectra of carbonyl sulfide and hydrogen cyanide are critically reviewed and tabulated. Molecular data such as rotational constants, centrifugal distortion constants, dipole moments, hyperfine coupling constants, and structural parameters are also tabulated. All rotational transitions from 100 MHz to 300 GHz that are deemed likely to be of interest to radio astronomers are calculated and tabulated along with their estimated 95 percent confidence limits. Microwave measurements are tabulated for most isotopic species and for many of the lower vibrational states. For both carbonyl sulfide and hydrogen cyanide a bibliography is given which includes nearly all the spectroscopic work reported in the literature. For each molecule a bibliography of related astrophysical papers is also given.

Rotational constants for HCN and DCN

Abstract Microwave measurements of rotational transitions within vibrationally excited states of several isotopic species of HCN have given improved values for the pertinent B v constants. These new data have been combined with infrared measurements given in the literature (ncluding D v terms) to arrive at a set of rovibrational constants (α and γ constants) which is consistent with all available data. Bond distances resulting from several different B e approximations are intercompared to assess the variability of the r e values and the importance of the γ terms. The latest r 0 and r s bond distances are also given.

Absolute frequency measurements of the 2-0 band of CO at 2.3 μm; Calibration standard frequencies from high resolution color center laser spectroscopy

Abstract The absolute frequencies of 20 lines of the 2-0 band of CO near 4260 cm −1 have been measured by heterodyne frequency measurement techniques. Eleven of the lines were measured by saturated absorption techniques which produced linewidths of about 3 MHz. New rovibrational constants have been fitted to these measurements. A table of calculated transition frequencies is given with estimated absolute uncertainties as small as 0.0000023 cm −1 (70 kHz) near the band center. The pressure shifts of three lines have been measured and fall in the range from −0.9 to −3 kHz/Pa (−122 to −400 kHz/Torr). It is suggested that the generally accepted frequencies of the 1-0 band of CO should be lowered by 7 MHz.

High temperature, high resolution infrared spectral measurements on the HNC–HCN equilibrium system

Spectral measurements have been made on HNC in equilibrium with HCN at temperatures ranging from 900 to 1250 K. From measurements of absorption intensity vs temperature it is determined that the ground state of HNC is 10.3±1.1 kcal/mol (43.1±4.6 kJ/mol) above the ground state of HCN. High resolution data are given on the following vibrational transitions for HNC near 3650 cm−1: 1000–0000, 1110–0110, 1200–0200, and 1220–0220. Measurements near 2780 cm−1 are also given for the 1000–0000 and 1110–0110 transitions for DNC. Aside from the low bending force constant, these measurements show nothing unusual about the bending potential function.

Heterodyne frequency measurements on the 11.6-μm band of OCS: new frequency/wavelength calibration tables for 11.6- and 5.8-μm OCS bands

Heterodyne difference frequency measurements between a (13)CO(2) laser and a diode laser tuned (and in most cases locked) to the peaks of OCS absorption lines have been used to improve frequency calibration tables in the 860-cm(-1) region by factors of 20-50. Measurements have been made on the vibrational transitions 10(0)0-00(0)0, 11(1)0-01(1)0, and 20(0)0-10(0)0 for OCS. The measurements on the 10(0)0-00(0)0 and 20(0)0-10(0)0 transitions are also used to provide frequency calibration tables for the 20(0)0-00(0)0 band of OCS near 1700 cm(-1).

Infrared measurements on allene and allene-d4☆☆☆

Abstract Several vibration-rotation absorption bands of allene (C 3 H 4 ) and allene- d 4 (C 3 D 4 ) have been measured with high resolution. From measurements of a parallel and a perpendicular band of C 3 H 4 the following constants were obtained: B 0 = 0.2963 2 ± 0.00006 cm −1 , D J = 11. 6 ± 2.4 × 10 −8 cm −1 and D JK = 4. 6 ± 1.8 × 10 −6 cm −1 . The best measurements on C 3 D 4 were for a parallel band at 2790.25 cm −1 for which the values B 0 = 0.2321 4 ± 0.00008 cm −1 and D J = 4. 1 ± 1.9 × 10 −8 cm −1 were obtained. By combining infrared and Raman measurements of ν 8 a value of A 0 = 4.807 ± 0.008 cm −1 was obtained. The resulting bond parameters are r 0 ( CC ) = 1.308 4 ± 0.0003 A , r 0 ( CH ) = 1.087 2 ± 0.0013 A , and 3 H 4 spectra are described.

Rotational constants of the lowest torsional component (0G) of the ground state and lowest torsional component (1G) of the first excited torsional state of hydrogen peroxide

Abstract New high-resolution spectra of hydrogen peroxide has been taken in the OH stretching region and in the overtone-combination region of the OOH bends. Ordinary combination differences in the (0G) and (1G) torsional states and directly obtained energy level differences between these torsional states have been supplemented with combination differences obtained from previously published microwave data and fitted to obtain the rotational constants of the two torsional states and the parameter characterizing the perturbation between them. A simplified notation scheme for the vibrational-torsional-rotational levels, the transitions used to obtain direct energy level differences between levels of the (0G) and (1G) torsional states, and the specific Hamiltonian used are described in the text. A table of rotational and interaction constants is given, and also tables of the actual (perturbed) rotational levels in the (0G) and (1G) torsional states.

Tables of N2O Absorption Lines for the Calibration of Tunable Infrared Lasers from 522 cm(-1) to 657 cm(-1) and from 1115 cm(-1) to 1340 cm(-1),

Data from the literature has been critically selected and refitted by least squares to provide accurate vibrational band centers and rotational constants for three bands of N2O. The line positions of the bands have been calculated from the constants of the fits to provide accurate absorption line positions to serve as wavelength standards in the regions of 522 cm−1 to 657 cm−1 and from 1115 cm−1 to 1340 cm−1 in the infrared.

High‐Resolution Infrared Spectra of Cyanogen and Cyanogen‐15N2

The infrared absorption of 12C214N2 and 12C215N2 has been studied with a resolution of 0.08 to 0.04 cm−1. The vibration—rotation band constants were determined for eight vibrational transitions of 12C214N2 and three vibrational transitions of 12C215N2. Many unresolved hot‐band Q branches were also measured. The values for many vibrational and rotational constants are given. The bond distances determined from the rotational analysis, and their three‐standard‐deviation error limits, are r0 (C–C) = 1.389±0.030 A and r0 (C≡N) = 1.154±0.017 A. The N–N distance and corresponding error limits are 3.697±0.010 A.