First stretching overtone of BiH3: An extreme local-mode case for XH3-type molecule?

Abstract

The first stretching overtone region of short-lived, formerly inaccessible BiH3 near 3405 cm(-1) has been measured by Fourier-transform infrared spectroscopy with a resolution of 0.0066 cm(-1). Only the 2nu1(A1)/nu1+nu3(E) band system has been observed. Rotational analysis, with transitions reaching J'max=14, has revealed almost perfect local-mode behavior for the upper states denoted as (200A1/E) in the local-mode notation. Ratios of vibration-rotation interaction parameters q(eff)/alpha(eff)(BB) and r(eff)/alpha(eff)(BC), and the appropriate rotational constant differences, are in good agreement with theoretical local-mode limit values. A simple stretching vibrational model reproduces the observed vibrational term values well, and the potential parameters obtained are close to true values.

High resolution infrared spectra of the first and second stretching overtone band systems of 123SbD3

“…A similar trend has already been observed in 120 SnD 4 with respect to 116 SnH 4 [21]. The nature of local mode character of 123 SbD 3 with respect to 123 SbH 3 can be further evidenced by evaluating the vibrational dependences of the effective parameters, which in case of true local mode limit, as in BiH 3 [14,39], are expressed by the following simple relations: where n is equal to v stretching .…”

“…The model used to analyze simultaneously the transitions of the interacting (A 1 /E) dyads, 2m 1 /m 1 + m 3 or 3m 1 /2m 1 + m 3 , is similar to that used for the m 1 and m 3 fundamentals [22], but with a different interpretation of the Hamiltonian coefficients. It has been successfully adopted in the analyses of the stretching overtones of AsH 3 , SbH 3 , and BiH 3 [12][13][14].…”

Rotational energy cluster formation in XY3 molecules: Excited vibrational states of BiH3 and SbH3

“…We label the overtone and combination levels by local-mode quantum numbers (lmnC vib ), where l, m, and n are the number of excited quanta in each of the three bond oscillators (see, for example, Ref. [12]), while C vib is the vibrational symmetry in C 3v (M) [3]. The three overtone and combination levels considered here, 2m 1 , m 1 + m 3 , and 2m 3 one state, each member of a cluster interacting to the same extent with a partner member of the same symmetry in the other cluster.…”

“…BiH 3 is a typical local-mode molecule [12] with a heavy central Bi atom bound to three much lighter H atoms. It has small intermode coupling and bond angles very close to 90°.…”

“…Variationally calculated term values (in cm À1 ) of BiH 3 and SbH 3 , compared to the available experimental data[12,19,20] …”