Vibration-rotation bands and rotational constants of dideuteroacetylene

1955 ◽  
Vol 232 (1190) ◽  
pp. 291-309 ◽  
Keyword(s):  
Resolving Power ◽  
Vibrational States ◽  
Absorption Bands ◽  
Rotational Constants ◽  
Vibrational Assignments ◽  
Vibrational Anharmonicity ◽  
A Value ◽  
Vibrational Levels ◽  
Vibration Rotation ◽  
Very High

Nine vibrational absorption bands of dideutero-acetylene have been examined with very high resolving power. The rotational constants have been determined for the vibrational levels concerned, and the coefficients α i have been determined with more convincing accuracy than previously. In some of the bands the Q branches have been resolved, so that the l -doubling coefficients q i could be derived, and details could be established about the doublet components in some II levels. The results emphasize the need of high resolution if the vibrational assignments are to be unambiguous, and if reliable values of the rotational constants are to be derived. A value of B e has been obtained, and the vibrational anharmonicity coefficients have been considered briefly. Estimates of the centrifugal stretching constants D i in different vibrational states have been made, and one anomalous case has been found.

Vibration-rotation bands and molecular constants of carbonyl sulphide

1954 ◽  
Vol 222 (1151) ◽  
pp. 431-443 ◽  
Keyword(s):  
Fermi Resonance ◽  
Resolving Power ◽  
Molecular Constants ◽  
Absorption Bands ◽  
Coriolis Interaction ◽  
Rotational Constants ◽  
Vibrational Levels ◽  
Vibration Rotation ◽  
Carbonyl Sulphide ◽  
First Time

The vibrational absorption bands of carbonyl sulphide 12 C 16 O 33 S near 5 μ have been examined using very high resolving power. Rotational fine structure has been resolved for the first time; six bands have been studied, including two associated with the isotopic species 13 C 16 O 33 S, and a rotational analysis of each has been carried out. Values have been derived for the rotational constants B and D in the different vibrational levels, and these have been compared with the results obtained from the microwave spectrum for the lower states. It has been found that the location of certain bands, and the rotational constants B are affected by Fermi resonance and Coriolis interaction, and estimates of the unperturbed values have been made.

SPECTRES DE VIBRATION-ROTATION DE MOLECULES SIMPLES DIATOMIQUES OU POLYATOMIQUES AVEC LONG PARCOURS D'ABSORPTION: XII. LE SPECTRE DE C12O162 ENTRE 3500 ET 8000 CM−1 ET LES CONSTANTES MOLECULAIRES DE CETTE MOLECULE

1957 ◽  
Vol 35 (5) ◽  
pp. 608-648 ◽  
Author(s):  
Charles-P. Courtoy
Keyword(s):  
Near Infrared ◽  
Fermi Resonance ◽  
Absorption Bands ◽  
Rotational Constants ◽  
Vibrational Levels ◽  
Coriolis Perturbation ◽  
Vibration Rotation ◽  
Experimental Values ◽  
Vibrational Constants ◽  
Usual Formula

Numerous absorption bands of the molecule C12O162 have been obtained in the near infrared under high resolution with the help of a multiple path absorption cell. Of these bands, 27 have been analyzed, among them three Δ—Δ transitions.The usual formula for the vibrational levels has been extended to include cubic terms and the values of the vibrational constants are given. Similarly the rotational constants Bν have been expressed by a formula including quadratic terms and the constants in this formula are given. The values of B0 and Be obtained here are respectively 0.39021 ±.00004 and 0.39162 cm−1.The l-type doubling constant qν of the Π states (apart from effects of Fermi resonance) can be represented by[Formula: see text].The perturbation term of the Fermi resonance is given by the expression[Formula: see text],where the quantum number l does not enter the first factor. The introduction of this expression allows one to represent all the vibrational levels as well as the rotational constants of each level and the constant q of the Π states with excellent precision.The value of D0 is found to be 13.5 × 10−8 cm−1. The effect of the Fermi resonance and of the perturbation between levels (ν1, ν2, l, ν3) and (ν1, ν2, l ± 2, ν3) on the constants D is discussed. The experimental values for these constants agree in a very satisfactory way with those calculated by Amat, Goldsmith, and Nielsen as do the constants μ of l-type doubling of the Π states.Finally the effect of Coriolis perturbation between the levels 3200 and (0511)c is demonstrated.

Vibration-rotation bands of acetylene and the molecular dimensions

1956 ◽  
Vol 238 (1212) ◽  
pp. 15-30 ◽  
Keyword(s):  
Molecular Vibrations ◽  
Rotational Constants ◽  
Bond Lengths ◽  
Vibrational Levels ◽  
Vibration Rotation ◽  
Molecular Dimensions

In view of recent inconsistencies in the relation between the bond lengths and rotational constants in the isotopic acetylenes, some vibration-rotation bands of acetylene have been re-measured, and the results have been analyzed together with earlier work on this molecule. The α values for each of the molecular vibrations have been re-determined, taking into account possible vibrational perturbations and also anomalous changes in the centrifugal stretching constant D of the different vibrational levels. The new values of α , 1 , α 2 , α 3 and ( α 4 + α 5 ) for acetylene are in line with the corresponding values for the deuterated derivatives, and using B o = 1·1766 lead to B e + 1·1817. If bond lengths r e (CH) = 1·058 5 , r e (CC) = l·204 7 Å are assumed, the results for all three isotopic molecules are mutually consistent. Values have also been obtained for the l -doubling coefficients, q 4 and q 5 .

Vibration-rotation bands of trideuteromethyl iodide

1965 ◽  
Vol 288 (1412) ◽  
pp. 39-49 ◽  
Keyword(s):  
Fine Structure ◽  
Coupling Constants ◽  
Coriolis Coupling ◽  
Molecular Constants ◽  
Rotational Constants ◽  
Vibrational Levels ◽  
Theoretical Predictions ◽  
Vibration Rotation ◽  
Combination Bands

The rotational fine structure of six parallel and nine perpendicular vibration bands of tri­deuteromethyl iodide has been analysed, and molecular constants have been derived. These include the band origins, the rotational constants in different vibrational levels, the α A i and α B i values, and the Coriolis coupling constants ς i for the fundamental degenerate vibrations. The ς values for overtone and combination bands have been compared with values calculated from the ς i values of the fundamentals, and agree closely with previous theoretical predictions.

Vibration-rotation bands of nitrous oxide

1951 ◽  
Vol 208 (1094) ◽  
pp. 326-331 ◽  
Keyword(s):  
Nitrous Oxide ◽  
Fine Structure ◽  
Ground State ◽  
Wave Length ◽  
The Other ◽  
Resolving Power ◽  
Microwave Measurements ◽  
Rotational Constants ◽  
Infra Red ◽  
Vibration Rotation

The infra-red absorption of nitrous oxide gas near 4·5 μ has been re-investigated using high resolving power. The rotational fine structure has been split up and shown to involve two vibrational transitions, one due to absorption of a fundamental from the ground state, and the other to a π → π transition from an excited vibrational level. The transitions have been analyzed theoretically and rotational constants obtained. The results serve to emphasize the importance of using more precise wave-length standards for infra-red measurements than have been used hitherto, if the rotational constants are to be obtained with accuracy com­parable to that achieved by microwave measurements. Excellent agreement with the latter has now been found.

Rotational analysis of the 2600a absorption system of benzene

1966 ◽  
Vol 259 (1104) ◽  
pp. 499-532 ◽  
Keyword(s):  
Excited States ◽  
Point Group ◽  
Vibrational Analysis ◽  
Resolving Power ◽  
Rotational Analysis ◽  
Absorption System ◽  
Vibrational Assignments ◽  
Anharmonic Constants ◽  
Equilibrium Configurations ◽  
Very High

The 2600A absorption system of benzene has been examined with very high resolving power, and the rotational fine structure partially analysed by comparison with computed contours. Vibronic bands involving degenerate e2g vibrations have contours characteristic of the vibrational angular momentum, and Coriolis coefficients £ have been determined for the lowest e2g vibrations in ground and B2u excited states. Band contours thus provide an additional criterion for checking vibrational assignments. In particular, values of £ determine the separation between band maximum and origin which can thus be calculated, and the vibrational analysis consequently refined in certainty and precision. Improved values of several fundamentals have been obtained, some new vibrational assignments made, and some previous ones rejected. Some important anharmonic constants have also been obtained. Vibronic relative intensities are briefly discussed. The rotational and vibrational evidence together make it certain that the equilibrium configurations of the carbon skeleton in benzene are exactly planar and hexagonal in both the ground and excited states, point group Z)6A. The rotational constants then give an estimate of the increase in G—C distance on excitation of + 0*038 A, in excellent agreement with estimates from other sources. The electronic origin of the system is revised: T00 = 38086*1 cm

A vibration-rotation band of monodeuteromethane

1953 ◽  
Vol 216 (1125) ◽  
pp. 143-152 ◽  
Keyword(s):  
Energy Levels ◽  
High Dispersion ◽  
Vibration Band ◽  
Hydrogen Atoms ◽  
Vibrational States ◽  
Fundamental Vibration ◽  
Type Band ◽  
Vibration Rotation ◽  
Two Sides ◽  
Very High

The fundamental vibration band of monodeuteromethane near 4-5 μ , connected with the stretching of the C—D bond, has been reinvestigated with very high dispersion. It provides a good example of well-resolved parallel-type band structure of a symmetric top molecule in which the K splitting of P and R lines is clearly seen. Alternations of intensity are also found in accordance with the nuclear spin of the three hydrogen atoms. The rotational constants B 0 and B 1 have been determined, giving r 0 (C—H) = 1.0924Å. The centrifugal stretching coefficient D J and its variation in the different vibrational states have also been measured. Analysis of the K splitting of the R and P lines reveals an anomaly between the sets on the two sides of the band origin, which seems to suggest that some unforeseen molecular interaction is neglected in the method at present accepted for calculating the molecular rotational energy levels.

Vibration bands and molecular rotational constants of nitrous oxide

1953 ◽  
Vol 220 (1143) ◽  
pp. 435-445 ◽  
Keyword(s):  
Nitrous Oxide ◽  
Fine Structure ◽  
High Resolution ◽  
Microwave Spectrum ◽  
Rotational Constants ◽  
Vibrational Levels ◽  
Resonance Interactions ◽  
Vibration Rotation ◽  
Different Levels

Seven vibration-rotation bands of nitrous oxide have been measured with high resolution. The rotational fine structure of each has been analyzed and rotational constants have been derived. The value for B 000 found from four bands is 0·4190 1 cm -1 , agreeing very closely with that determined from the microwave spectrum. Values for the coefficients α i for the different vibrational levels have been determined, and the occurrence of inconsistencies in the calculated values of B v 1 v 2 v 3 for higher vibrational levels confirms previous suggestions that resonance interactions may exist between different levels. Such interactions appear also to disturb the positions of the band origins.

Vibration-rotation bands of monodeuteroacetylene and the molecular dimensions

1956 ◽  
Vol 234 (1198) ◽  
pp. 306-317 ◽  
Keyword(s):  
High Resolution ◽  
Ground State ◽  
Fermi Resonance ◽  
Rotational Constants ◽  
Bond Lengths ◽  
Vibrational Levels ◽  
Vibration Rotation ◽  
Molecular Dimensions

Some vibration-rotation bands of monodeuteroacetylene have been measured with high resolution. Values have been derived for the coefficients α i relating the rotational constants in different vibrational levels, as follows: α 2 = + 0⋅00439, α 3 = + 0⋅00638, α 4 = — 0⋅0032 2 , α 5 = — 0⋅0011. Using the value B 00000 = 0⋅9910 5 cm -1 , also determined from many bands, a new value, B e = 0⋅9948, has been obtained leading to new estimates for the bond lengths r e CH = 1⋅058 Å, and r e C≡C = 1⋅205 0 . The l -doubling coefficient has been determined in two states, namely, q 00010 = 0⋅0056 and q 00003 = 0⋅0072. In the ground state the results are in accordance with a centrifugal stretching coefficient D = 0⋅7 x 10 -6 , but in some higher levels a markedly different value is derived, which may, however, arise through the effects of Fermi resonance.

BANDE DE VIBRATION–ROTATION ν1 + ν4 DE L'IODURE DE MÉTHYLE TRIDEUTÉRIÉ VERS 4 500 cm−1 : MISE EN ÉVIDENCE D'UNE RÉSONANCE DE FERMI

1966 ◽  
Vol 44 (11) ◽  
pp. 2695-2707 ◽  
Author(s):  
C. Joffrin ◽  
Nguyen Van Thanh ◽  
P. Barchewitz
Keyword(s):  
Spectral Range ◽  
Fermi Resonance ◽  
Resolving Power ◽  
Rotational Constants ◽  
Vibration Rotation

The perpendicular band (ν1 + ν4) of CD3I was recorded with a Czerny-type spectrometer, the resolving power of which was about 80 000 in the spectral range. Some rotational constants have been found, and the Fermi resonance between the ν1 + ν4 and ν4 + 2ν5 components pointed out.

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