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.

Characteristic Normal Modes of Vibration and Generalized Normal Forces: Basic Properties and Relation to Fundamental Molecular Constants

1980 ◽  
Vol 35 (11) ◽  
pp. 1142-1151
Author(s):  
A. J. P. Alix ◽  
E. Rytter
Keyword(s):  
Normal Modes ◽  
Coupling Constants ◽  
Molybdenum Hexacarbonyl ◽  
Molecular Constants ◽  
Energy Distributions ◽  
Normal Forces ◽  
Isotopic Shifts ◽  
Modes Of Vibration ◽  
Restoring Forces ◽  
Secular Equations

Abstract A survey is given of the simplified formulae for energy distributions, force constants, secular equations, Coriolis coupling constants, isotopic substitutions, compliances, mean amplitudes, bond moment and polarizability parameters, interaction coordinates and restoring forces in the cases where either a completely characteristic normal mode or a generalized normal force can be assumed. The obtained results may be of use for the following main purposes: (i) computation of quantities which can be employed in the assignment of spectra, band shapes, intensities ... (ii) evaluation of fundamental molecular constants and isotopic shifts which can be approximated with good accuracy. As illustration, the equations have been applied sucessfully to two-dimensional cases and to Molybdenum-hexacarbonyl.

A study of the electric quadrupole fundamental band of D2 using an infrared difference frequency laser system

1978 ◽  
Vol 56 (10) ◽  
pp. 1315-1320 ◽  
Author(s):  
A. R. W. McKellar ◽  
T. Oka
Keyword(s):  
Laser System ◽  
Electric Quadrupole ◽  
Difference Frequency ◽  
Ratio Method ◽  
Molecular Constants ◽  
Frequency Tunable ◽  
Vibration Rotation ◽  
Frequency Laser ◽  
Deuterium Molecule ◽  
Rotation Spectrum

Frequency tunable infrared radiation from a difference frequency laser system has been used with a long path cell to study the electric quadrupole vibration–rotation spectrum of the deuterium molecule in the 2.8–3.9 μm region. A ratio method as well as frequency modulation were used to detect the weak absorption. Sub-Doppler linewidths due to collisional narrowing were observed with a D2 pressure of 1 atm. The wavelengths of 11 transitions were measured relative to infrared reference lines, and improved molecular constants for the ν = 0 and 1 states of D2 were determined.

Spectre d'émission de la molécule PO: Transitions C′2Δ–X2Πr et C2Σ−–X2Πr de P16O et P18O

1973 ◽  
Vol 51 (23) ◽  
pp. 2464-2473 ◽  
Author(s):  
J. C. Prudhomme ◽  
M. Larzillière ◽  
C. Couet
Keyword(s):  
Fine Structure ◽  
Vibrational Level ◽  
Rotational Analysis ◽  
Molecular Constants ◽  
Vibrational Levels ◽  
State 1

The rotational analysis of 11 bands of the C′–X2Πr system is carried out and has allowed the study of vibrational levels of the C′ state: 1, 2, 3, 4 for P16O and 0, 2, 3, 4 for P18O. The nature of the C′ state is confirmed as a 2Δ state. New molecular constants are proposed.The analysis of the fine structure of 4 bands of the C2Σ−–X2Πr transition of P18O shows that the lowest vibrational level of the C state, which has been characterized previously for P16O, is the level ν = 1. The molecular constants of this state have been modified on account of the new identification.The fine doubling of the X2Π, C′2Δ, and C2Σ− are discussed.

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.

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.

The Band System of Propynal: Rotational Analysis of the 0–0 Band Near 4145 Å

1973 ◽  
Vol 51 (17) ◽  
pp. 1810-1814 ◽  
Author(s):  
F. W. Birss ◽  
Ronald Y. Dong ◽  
D. A. Ramsay
Keyword(s):  
High Resolution ◽  
Band System ◽  
Transition Moment ◽  
Magnetic Rotation ◽  
Rotational Analysis ◽  
Molecular Constants ◽  
Rotation Spectrum

The 0–0 band of the [Formula: see text] system of propynal near 4145 Å has been photographed under high resolution and a rotational analysis carried out. The principal molecular constants for the ã3A″ state are (in cm−1):[Formula: see text]Altogether, 1237 lines have been assigned to transitions with ΔKa = 0. The dominant transition moment involves mixing of the ã3A″ state with higher 1A′ states.A simple magnetic rotation spectrum has been obtained and the assignments of the lines discussed.

scholarly journals Preparation and the Microwave and Infrared Spectra of Vinyl Ketene

1979 ◽  
Vol 34 (11) ◽  
pp. 1269-1274 ◽  
Author(s):  
Erik Bjarnov
Keyword(s):  
Dipole Moment ◽  
Gas Phase ◽  
Infrared Spectra ◽  
Room Temperature ◽  
Normal Modes ◽  
Spectroscopic Constants ◽  
Electrical Dipole ◽  
Electrical Dipole Moment ◽  
Vacuum Pyrolysis ◽  
Modes Of Vibration

Vinyl ketene (1,3-butadiene-1-one) has been synthesized by vacuum pyrolysis of 3-butenoic 2-butenoic anhydride. The microwave and infrared spectra of vinyl ketene in the gas phase at room temperature have been studied. The trans-rotamer has been identified, and the spectroscopic constants were found to be Ã= 39571(48) MHz, B̃ = 2392.9252(28) MHz, C̃ = 2256.0089(28) MHz, ⊿j = 0.414(31) kHz, and ⊿JK = - 34.694(92) kHz. The electrical dipole moment was found to be 0.987(23) D with μa = 0.865(14) D and μb = 0.475(41) D. A tentative assignment has been made for 17 of the 21 normal modes of vibration

Normal modes of vibration of a model peptide adopting the C7 C5 structure

2009 ◽  
Vol 24 (6) ◽  
pp. 543-552 ◽  
Author(s):  
P. LAGANT ◽  
G. VERGOTEN ◽  
G. FLEURY ◽  
M.H. LOUCHEUX-LEFEBVRE
Keyword(s):  
Normal Modes ◽  
Model Peptide ◽  
Modes Of Vibration
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