Difference of Upper and Lower State Rotational Constants of Symmetrical‐Top Molecules from Infrared Intensity Measurement

1960 ◽  
Vol 32 (5) ◽  
pp. 1574-1575
Author(s):  
Tsuneo Yoshino
Keyword(s):  
Intensity Measurement ◽  
Lower State ◽  
Rotational Constants ◽  
Infrared Intensity

NEW ELECTRONIC TRANSITIONS OF THE BH MOLECULE

1941 ◽  
Vol 19a (2) ◽  
pp. 27-31 ◽  
Author(s):  
A. E. Douglas
Keyword(s):  
Electronic Transitions ◽  
Lower State ◽  
Electron Configuration ◽  
Rotational Constants ◽  
Boron Trichloride ◽  
New States ◽  
Π State

In a discharge in helium with a trace of boron trichloride and hydrogen three new bands are found at 3415 Å, 3396 Å, and 3099 Å. Measurements of these bands show that they are due to two new electronic transitions of the BH molecule. The upper states of both transitions are previously unknown 1Σ+ states. The lower state of both transitions is the same and is a known 1Π state. The rotational constants of both new states have been determined and their electron configuration is suggested.

New spectrum of the SiO+ molecule

1968 ◽  
Vol 46 (14) ◽  
pp. 1597-1602 ◽  
Author(s):  
S. Nagaraj ◽  
R. D. Verma
Keyword(s):  
Rotational Structure ◽  
Lower State ◽  
Weak Band ◽  
Rotational Constants

A new spectrum of SiO+ in the region 4300–4100 Å has been obtained by a r-f. discharge through a flowing mixture of argon and SiCl4 which contained a trace of oxygen. This spectrum is mainly a long sequence Δν = 0. The rotational structure of the three bands 0–0, 1–1, and 2–2 has been analyzed and the rotational constants of the upper and lower states are determined.The known spectrum of SiO+ in the region around 3840 Å (Woods 1943) has also been obtained, with improved intensity under the above conditions and has been reanalyzed. It is found that the earlier numbering of the lines of this system is wrong by one unit and that the lower state of these bands and the upper state of the new bands represent the same state. The weak band, which was analyzed by Woods as 1–1, appears to fit as 2–2 according to the new analysis.Rotational constants of the three 2Σ states, which are named X, A, and B, are shown below (in cm−1):[Formula: see text]A discussion on electron configurations has also been included.

SPECTRUM AND STRUCTURE OF THE BORON MONOSULPHIDE (BS) MOLECULE

1951 ◽  
Vol 29 (4) ◽  
pp. 336-356 ◽  
Author(s):  
P. B. Zeeman
Keyword(s):  
Discharge Tube ◽  
Lower State ◽  
Rotational Constants

Two band systems of the BS molecule, called the α and γ systems, have been excited in a discharge through B2S3 vapor in a quartz discharge tube. Vibrational and rotational analyses of these systems have been carried out, and it is shown that both systems have the same lower state, which is a 2Σ state. Both the upper states are 2Π states. The α system is analogous to the α system of BO, but the γ system has not been observed for BO. Tables giving the vibrational and rotational constants of the various states are given. A third system of strong bands in the blue–green region is observed simultaneously with the α and γ bands in the discharge. These bands have not yet been interpreted. By means of the observed isotopic bands, it has been proved that BS is the emitter of the α and γ systems.

scholarly journals The absorption spectrum of bromine in the near infra-red

1937 ◽  
Vol 159 (896) ◽  
pp. 93-109 ◽  
Keyword(s):  
Absorption Spectrum ◽  
Isotope Effect ◽  
Numerical Data ◽  
Lower State ◽  
Rotational Constants ◽  
Dissociation Energies ◽  
Main System ◽  
Infra Red ◽  
True Quantum ◽  
Vibrational Isotope Effect

Vibrational analyses of the absorption spectrum of bromine were first published in 1926 by Kuhn (1926) and by Nakamura (1926). Kuhn’s measurements covered the range 5117-6722 A except for the region 5280- 5550 A., where the band-heads were too indefinite for measurement. As a result of this gap an error of 5 units in K uhn’s v' numeration was subsequently shown to have arisen (Birge 1929). Nakam ura’s observations extended from 5130 to 7586 A but did not fit a v ', v " table satisfactorily. Neither observer recorded isotope band-head measurements. In 1931 Browne stablished the existence of two absorption systems in the range 5113- 7605 A; one, referred to as the main system, consisting of six v ' progressions between 5113 and 6590 A, and the other, an extreme red system, consisting of five v ' progressions between 6448 and 7605 A. These systems are attributed to the transitions 3 Π 0+ u ← 1Σ + g and 3 Π 1+ u ← 1Σ + g respectively. Observations of the vibrational isotope effect in the main system due to the existence of two isotopes enabled him to determine the true quantum numeration in the upper state of this system. The assignment thus made was later confirmed by him (Brown 1932) from his analysis of the fine structure of bands of this system. The vibrational and rotational constants and the dissociation energies associated with the lower and upper states of the main system are now known fairly completely and accurately. The numerical data are consistent with the view that dissociation of the lower state leads to two normal 2 P 3/2 atoms, whilst dissociation of the upper state yields a normal 2P | atom and an excited 2 P 1/2 atom. The lower state of the extreme red system is identical with that of the main system, but as no measurement of the vibrational isotope effect and no rotational analysis for the extreme red system has been reported so far, the true quantum numeration, the vibrational and rotational constants and the dissociation energy of the upper state are not known accurately. From observations of the bands in each progression for which the heads are sharpest and the assumption that these are the points where the isotope effect changes sign, Brown was led to suggest that his arbitrary numeration should be increased by 4 ± 2 units. When the Morse potential energy curves are drawn assuming the provisional numeration to be correct (Jevons 1932; Sponer 1935), calculating r'e from the approximate empirical rule

The absorption spectrum of the free NCO radical

1960 ◽  
Vol 252 (1007) ◽  
pp. 165-192 ◽  
Keyword(s):  
Flash Photolysis ◽  
Ultra Violet ◽  
Fermi Resonance ◽  
Spin Splitting ◽  
Lower State ◽  
State Transitions ◽  
Absorption Bands ◽  
Bending Vibration ◽  
Rotational Constants ◽  
Coupling Case

Two systems of absorption bands have been observed in the visible and ultra-violet regions of the spectrum during the flash photolysis of several organic cyanates, and have been photographed under high resolution with long absorbing paths. Extensive vibrational and rotational analyses have been carried out for the bands of one system and show that the spectrum is due to an electronic transition A ( 2 Z + ) <-- X ( 2 II < i ) of the free NCO radical, which is linear in both states. All three vibrational frequencies and the first-order anharmonic constants have been obtained for the upper state, A ( 2 { + ), and give a close fit to the term values of 21 observed vibrational levels. A Fermi resonance has been observed between v ' 1 and 2v' 2 . In addition, the rotational constants B' and D' and their variations with all three fundamental vibrations have been obtained for this state. Transitions have been observed from four excited levels of the bending vibration in the lower state, X ( 2 II i ), and the rotational constants have been determined for some of these levels. Interaction between the electronic and vibrational motions (Renner effect) complicates the vibrational structure of this state. The state belongs to Hund’s coupling case ( a ), and the spin-orbit coupling gives a splitting A" = —95.6 cm<super>-1</super>. In a 2 { + vibronic level of this state (arising from l = 1 and A = 1) the spin sp litting is proportional to N +1/2, but the spin-splitting constant y is unusually large, and amounts to 30 % of the B value. The electronic states of NCO are correlated with those of its dissociation products. This shows that the bond dissociation energy of the CO bond is slightly greater than that of the CN bond in the three known states.

A 4Σ−–2Π TRANSITION OF THE SiF MOLECULE

1962 ◽  
Vol 40 (5) ◽  
pp. 586-597 ◽  
Author(s):  
R. D. Verma
Keyword(s):  
High Resolution ◽  
Ground State ◽  
Electronic States ◽  
Lower State ◽  
Rotational Analysis ◽  
Rotational Constants

The η bands of SiF, in the region 3300–3400 Å, have been photographed in emission at high resolution. A detailed rotational analysis has shown that these bands represent a 4Σ−–2Πτ transition. The lower state is the ground state of the molecule. The principal rotational constants of the upper and lower electronic states in cm−1 are as follows:[Formula: see text]A discussion of the electron configurations is also given.

ROTATIONAL ANALYSIS OF THE γ SYSTEM OF THE PO MOLECULE

1958 ◽  
Vol 36 (11) ◽  
pp. 1526-1535 ◽  
Author(s):  
K. Suryanarayana Rao
Keyword(s):  
Ground State ◽  
Electronic Transition ◽  
Lower State ◽  
High Dispersion ◽  
Rotational Analysis ◽  
Small Perturbations ◽  
Rotational Constants ◽  
The One

The bands of the γ system of the PO molecule have been photographed under high dispersion (0.35 Å/mm). A rotational analysis of the 0–0, 0–1, and 1–0 bands is given, which differs from the one previously given by Sen Gupta. In addition, four more bands, namely, the 1–2, 2–1, 2–3, and 2–4 bands, have been analyzed. The bands are attributed to the electronic transition, A3Σ–X2Πreg, the lower state being the ground state of the molecule. The new rotational constants for the ground state are the following:[Formula: see text]The spin doubling in the upper state is small. Perturbations in the v = 0 level of the upper state, which were not reported previously, are observed and discussed. They supply a welcome confirmation of the correctness of the analysis here presented.

Sign in / Sign up

Export Citation Format

Share Document