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High resolution Fourier transform infrared spectral analysis of the vibrational-rotational structure of acetylene (C2H2)
Author
Schultz, Ingmar Soren
Supervisor
Tan, Augustine Tuck Lee
Abstract
High resolution infrared absorption experiments were performed with a Fourier transform infrared spectrophotometer to measure the vibration-rotational spectrum of various hot bands of the C2H2 molecule in the region between 664 to 790 cm-' with a pressure of 10 mbar and an ambient temperature of 296K at a unapodized resolution of 0.002 cm-'.
The hot bands 2v5 - v5( - II), 2v5 - v5 (Σ - II) , v4 + v5 - V4 ( - II) , v4 +v5 -v4 (Σ+ - II ) , v4 +v5 -v4 ( Σ- -II) of 12C2H2 and the v5 (II-Σ) fundamental band of 12C13CH2 were examined closer.
A least square-fitting program for linear molecules was used to fit the observed line frequencies with a rms deviation of about 10-5 cm-'. A set of rotational-vibrational constants and their band centres for each of the bands mentioned above was determined to high level of accuracy. Most of the calculated frequencies agree with the observed frequencies to an accuracy better than 0.003 cm-'. The accurate wave number transitions, which are observed and analysed in this investigation are useful as secondary wave number calibration standards for infrared bands.
The hot bands 2v5 - v5( - II), 2v5 - v5 (Σ - II) , v4 + v5 - V4 ( - II) , v4 +v5 -v4 (Σ+ - II ) , v4 +v5 -v4 ( Σ- -II) of 12C2H2 and the v5 (II-Σ) fundamental band of 12C13CH2 were examined closer.
A least square-fitting program for linear molecules was used to fit the observed line frequencies with a rms deviation of about 10-5 cm-'. A set of rotational-vibrational constants and their band centres for each of the bands mentioned above was determined to high level of accuracy. Most of the calculated frequencies agree with the observed frequencies to an accuracy better than 0.003 cm-'. The accurate wave number transitions, which are observed and analysed in this investigation are useful as secondary wave number calibration standards for infrared bands.
Date Issued
1999
Call Number
QD95 Sch
Date Submitted
1999