Premium
Spectroscopic Determination of the Hindered Rotational Behavior of the CN − in Alkali Halides
Author(s) -
Wilk S. R.,
Lüty F.
Publication year - 1988
Publication title -
physica status solidi (b)
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.51
H-Index - 109
eISSN - 1521-3951
pISSN - 0370-1972
DOI - 10.1002/pssb.2221460132
Subject(s) - moment of inertia , halide , alkali metal , chemistry , ion , excitation , atomic physics , spectral line , rotational temperature , analytical chemistry (journal) , moment (physics) , molecular physics , physics , molecule , inorganic chemistry , organic chemistry , chromatography , quantum mechanics , astronomy , classical mechanics
The rotational properties of CN − substituted into various alkali halide matrices are studied through the rotational‐vibrational second harmonic absorption and excitation spectra at 2.4 μm of its vibrational emission. The variation of the spectral width with temperature is measured through the separation of the R‐ and P‐branches, the full width at half maximum, or the second moment of the spectra. The onset of T 1/2 variation of the width provides a direct, if rough, measurement of the height of the barrier hindering quasifree rotation. This barrier varies from 20 cm −1 in KI to 85 cm −1 in CsCl. The coefficients of T 1/2 yield the rotational constant, which varies from 0.16 cm −1 in CsI to 1.36 cm −1 in KCl. Since all measured values fall below the expected free CN − value of 1.94 cm −1 , the effective moment of inertia must be increased by some mechanism, among which dressing of the ion's moment of inertia by participation of the surrounding lattice ions in rotational motion is judged to be most likely.