Optimum molecular constants and term values for the X2Π(ν ≤ 5) and A2Σ+(ν ≤ 3) states of OH

1980 ◽  
Vol 58 (7) ◽  
pp. 933-949 ◽  
Author(s):  
J. A. Coxon
Keyword(s):  
Least Squares ◽  
Vibrational Level ◽  
Molecular Constants ◽  
Microwave Frequencies ◽  
X Band ◽  
Data Tables ◽  
Vibration Rotation

Least-squares fits of 1618 A2Σ+–X2Π frequencies, 774 X2Π vibration–rotation frequencies, and 125 microwave frequencies have been made to effective 2Σ+ and 2Π Hamiltonians containing adjustable parameters for each vibrational level. The fitted parameters from each band, some of which included the microwave frequencies simultaneously, have been merged to obtain a set of 13 A ↔ X band origins and 91 single-valued parameters for A2Σ+, ν ≤ 3 and X2Π, ν ≤ 5. The set of parameters reproduces the experimental frequencies with residuals which on the average are only about 1.12 times larger than the estimated precisions of the data. Tables of term values calculated from the merged constants are reported for the two states.

The Vibration–Rotation Spectrum of Ammonia Gas. II. A Rotational Analysis of the 6450 A Band

1972 ◽  
Vol 50 (2) ◽  
pp. 93-102 ◽  
Author(s):  
J. O. P. McBride ◽  
R. W. Nicholls
Keyword(s):  
Vibrational Level ◽  
Normal Modes ◽  
Rotational Analysis ◽  
Molecular Constants ◽  
Ammonia Gas ◽  
Modes Of Vibration ◽  
Vibrational Energies ◽  
Temperature And Pressure ◽  
Vibration Rotation ◽  
Rotation Spectrum

A rotational analysis of the 5ν1 (6450 A) band in the vibration–rotation spectrum of ammonia is presented here. The QP, QQ, and QR branches of a parallel transition are observed for values of J′ and K′ less than 6. Members of the SQ and OQ branches are observed with very low intensity. The molecular constants of the molecule in the (5, 0, 0, 0) vibrational level were determined; the N–H bond length is 1.015 ± 0.005 A and the bond angle is 112.0 ± 0.8° for this vibrational level. The potential energy to inversion of the molecule by excitation of the ν1 vibration only is 51 800 ± 1200 cm−1. The width of individual rotational lines increases with increase in J′ and K′. This increase in width is characteristic of a tunnelling mechanism. It may be due to the interaction between the normal modes of vibration at large vibrational energies. This analysis should improve the usefulness of the 6450 A band of ammonia for monitoring the temperature and pressure of the Jovian atmosphere.

Rotational analysis of hydroxyl vibration–rotation emission bands: Molecular constants for OH X2Π, 6 ≤ ν ≤ 10

1982 ◽  
Vol 60 (1) ◽  
pp. 41-48 ◽  
Author(s):  
J. A. Coxon ◽  
S. C. Foster
Keyword(s):  
Hydroxyl Radical ◽  
Least Squares ◽  
Orbit Coupling ◽  
Spin Orbit Coupling ◽  
Spin Orbit ◽  
Rotational Analysis ◽  
Coupling Constant ◽  
Molecular Constants ◽  
Vibration Rotation ◽  
Measured Line

Seven vibration–rotation emission bands of the hydroxyl radical with 6 ≤ ν′ ≤10 have been recorded photoelectrically in the range λ6250–8500 Å. The first reliable constants for levels 6 ≤ ν ≤10 of OH X2Π are obtained by direct least-squares fitting of the measured line frequencies. The vibrational dependences of the Λ-doubling parameters (p and q) and the spin–orbit coupling constant (A) are well defined. A minimum value of Aν is found at ν = 7.

Millimetre wave spectrum of methyl mercaptan

1980 ◽  
Vol 58 (11) ◽  
pp. 1640-1648 ◽  
Author(s):  
R. M. Lees ◽  
M. Ali Mohammadi
Keyword(s):  
Interstellar Medium ◽  
Least Squares ◽  
Wave Spectrum ◽  
Methyl Mercaptan ◽  
Rotational Spectrum ◽  
Centrifugal Distortion ◽  
Millimetre Wave ◽  
Torsion Vibration ◽  
Vibration Rotation ◽  
Centrifugal Distortion Constants

An investigation of the rotational spectrum of CH332SH, one of the most recent molecules to be detected in the interstellar medium, has been carried out over the 25–107 GHz region. The frequencies of a-type Δk = 0 R-branch transitions have been measured for the J = 1 ← 0 up to J = 4 ← 3 multiplets for torsional states νt = 0–3. In addition, many P-, Q-, and R-branch transitions with Δk ≠ 0 have been identified in order to provide a catalogue of lines for potential radio astronomical applications. Improved values of rotational and centrifugal distortion constants, a-type torsion–vibration–rotation interaction constants, and torsional barrier parameters (V3 = 444.76 cm−1; effective V6 = −2.07 cm−1) have been determined from least-squares analyses of the spectra.

On the b1Σ–X3Σ transitions of SeO and AsF

1978 ◽  
Vol 56 (10) ◽  
pp. 1399-1401 ◽  
Author(s):  
P. Kristiansen
Keyword(s):  
Least Squares ◽  
Linear Models ◽  
Linear Least Squares ◽  
Molecular Constants ◽  
Non Linear

A non-linear least-squares procedure has been used to determine molecular constants for SeO and AsF from the b1Σ–X3Σ transitions. The present investigation strongly indicates that the original J-numbering based on combination differences and linear models is incorrect for some of the branches.

High-resolution laser-excitation spectrum of the A2Π ← X2Σ system of TiN: rotational analysis of the 0–0, 1–1, and 2–2 bands

1985 ◽  
Vol 63 (7) ◽  
pp. 997-1004 ◽  
Author(s):  
K. Brabaharan ◽  
J. A. Coxon ◽  
A. Brian Yamashita
Keyword(s):  
High Resolution ◽  
Least Squares ◽  
Excitation Spectrum ◽  
Laser Excitation ◽  
Rotational Analysis ◽  
Molecular Constants ◽  
Individual Bands ◽  
Measured Line ◽  
Line Positions ◽  
Π State

The 0–0, 1–1, and 2–2 bands of the A2Π ← X2Σ system of TiN have been recorded using the technique of laser-excitation spectroscopy. Molecular constants have been obtained from direct least squares fits of the measured line positions of individual bands. The fitted constants confirm and extend previous determinations; for the A2Π state, some of the constants show unusually large variations with ν, in accord with the already known perturbation of this state in the ν = 0 level.

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