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Precision Lamb-dip infrared spectra of the C-N stretching band of CH(3)NH(2) with a CO(2)-laser/microwave-sideband spectrometer
- Source :
- The Journal of chemical physics. 132(19)
- Publication Year :
- 2010
-
Abstract
- We report saturation dip spectroscopy in the C-N stretching band of CH(3)NH(2) with a resolution of 0.4 MHz and an accuracy of 0.1 MHz by use of a CO(2)-laser/microwave-sideband spectrometer. The wide tunability, Lamb-dip resolution, absolute frequency accuracy, and high sensitivity of our dual-mode instrument were all key features in making precise measurements for a range of lines in the densely crowded spectrum with its complex pattern of splittings arising from the large-amplitude CH(3) torsion and NH(2) inversion. We focused on achieving resolution and assignment of transitions within the highly blended Q branch of the C-N stretch and on observations of the important K=0 sequences of Aa and Ea torsion-inversion symmetry. Term values of the latter were fitted to J(J+1) power-series expansions to obtain the K=0 C-N stretching effective B values and substate origins, from which calculated ground-state substate energies were subtracted to yield values of 1044.7061 and 1044.8011 cm(-1) for the Aa and Ea subband origins, respectively. We thereby estimate a mean value of 1044.75(5) cm(-1) for the vibrational band origin and 0.7323(5) cm(-1) for the effective upper-state B value for the C-N stretching fundamental of CH(3)NH(2).
- Subjects :
- Spectrometer
Sideband
Spectrophotometry, Infrared
Chemistry
Lasers
Analytical chemistry
General Physics and Astronomy
Infrared spectroscopy
Torsion (mechanics)
Carbon Dioxide
Molecular physics
Lamb shift
Methylamines
Physical and Theoretical Chemistry
Saturation (chemistry)
Spectroscopy
Microwaves
Microwave
Subjects
Details
- ISSN :
- 10897690
- Volume :
- 132
- Issue :
- 19
- Database :
- OpenAIRE
- Journal :
- The Journal of chemical physics
- Accession number :
- edsair.doi.dedup.....a842a804dc7d894acf0a4ace4ce5d1a5