TOWARDS A GLOBAL FIT OF THE COMBINED MILLIMETER-WAVE AND HIGH RESOLUTION FTIR DATA FOR THE LOWEST EIGHT VIBRATIONAL STATES OF HYDRAZOIC ACID (HN3)

Woods, R. Claude

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Description

Title

TOWARDS A GLOBAL FIT OF THE COMBINED MILLIMETER-WAVE AND HIGH RESOLUTION FTIR DATA FOR THE LOWEST EIGHT VIBRATIONAL STATES OF HYDRAZOIC ACID (HN3)

Author(s)

Woods, R. Claude

Contributor(s)

• McMahon, Robert J.
• Esselman, Brian J.
• Amberger, Brent K.

Issue Date

26-Jun-15

Keyword(s)

Small molecules

Abstract

Hydrazoic acid (chem{HN_3}) is a near-prolate asymmetric top molecule which we have extensively studied in the millimeter-wave region. Having completed an emph{R}$_{e}$ structure determination based on 14 isotopologues of chem{HN_3}, we have moved on to analyze the very complex rotational spectra for the first 7 vibrationally excited states, as well as the higher emph{K} levels of the ground vibrational state. The excited states include the 4 lowest (out of 6) fundamental modes (nub{5}, nub{6}, nub{4}, and nub{3}) and the 3 lowest combination and overtone states (2nub{5}, 2nub{6} and nub{5}+nub{6}). All of these states are totally symmetric (emph{A�}) except for nub{6} and nub{5}+nub{6}, which are antisymmetric (emph{A�}). The ro-vibrational states are substantially more intermingled than in most molecules due to unusually wide rotational spacing in chem{HN_3}. This intermingling leads to a tangled web of perturbations connecting the various ro-vibrational states: emph{a}-type and emph{b}-type Coriolis interactions between nub{5} and nub{6}, between nub{4} and nub{6}, and between 2nub{6} or 2nub{5} and nub{5}+nub{6}, local Fermi resonance between nub{3} and 2nub{6}, and a strong centrifugal distortion interaction between the ground state and nub{5}. Fortunately, we have been able to make extensive use (in both assignment of spectra and fitting of spectroscopic parameters) of previously published high resolution FTIR data for the nub{5}, nub{6}, nub{4} and nub{3} bands and the pure rotational spectrum of the ground vibrational state.footnote{J. Bendtsen, F. Hegelund and F. M. Nicolaisen, emph{J. Mol. Spectrosc.} textbf{118}, 121 (1986)}$^{,}$footnote{J. Bendtsen and F. M. Nicolaisen, emph{J. Mol. Spectrosc.} textbf{119}, 456 (1986)}$^{,}$footnote{J. Bendtsen and F. M. Nicolaisen, emph{J. Mol. Spectrosc.} textbf{124}, 306 (1987)}$^{,}$footnote{J. Bendtsen and F. M. Nicolaisen, emph{J. Mol. Spectrosc.} textbf{152}, 101 (1992)} For the ground state, emph{a}-type R-branches from emph{K} = 0 to emph{K} = 9 and emph{J} = 9 through emph{J} = 19 and emph{b}-type transitions with emph{K} = 0 through emph{K} = 2 and emph{J} values up to 56 have been assigned. The datasets for most other states are similarly extensive. Combined millimeter-wave/FTIR multi-state fits have been performed using Pickett�s SPFIT program.

Publisher

International Symposium on Molecular Spectroscopy

Type of Resource

text

Language

English

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