High-resolution infrared spectra of bicyclo[1.1.1]pentane

Journal Article · Thu Jul 01 00:00:00 EDT 2010 · Journal of Molecular Spectroscopy

DOI:https://doi.org/10.1016/j.jms.2010.04.010· OSTI ID:989432

Martin, M. A.; Perry, A.; Masiello, T.; Schwartz, K. D.; Nibler, J. W.; Weber, A.; Maki, A.; Blake, T. A.

Infrared spectra of bicyclo[1.1.1]pentane (C5H8) have been recorded at a resolution (0.0015 cm-1) sufficient to resolve for the first time individual rovibrational lines. This initial report presents the ground state constants for this molecule determined from the detailed analysis of three of the ten infrared-allowed bands, v14(e') at 540 cm-1, v17(a2'') at 1220 cm-1, v18(a2'') at 832 cm-1, and a partial analysis of the v11(e') band at 1237 cm-1. The upper states of transitions involving the lowest frequency mode, v14(e'), show no evidence of rovibrational perturbations but those for the v17 and v18 (a2'') modes give clear indication of Coriolis coupling to nearby e' levels. Accordingly, ground state constants were determined by use of the combination-difference method for all three bands. The assigned frequencies provided over 3300 consistent ground state difference values, yielding the following constants for the ground state (in units of cm-1): B0 = 0.2399412(2), DJ = 6.024(6) x 10-8, DJK = -1.930(21) x 10-8. For the unperturbed v14(e') fundamental, more than 3500 transitions were analyzed and the band origin was found to be at 540.34225(2) cm-1. The numbers in parentheses are the uncertainties (two standard deviations) in the values of the constants. The results are compared with those obtained previously for [1.1.1]propellane and with those computed at the ab initio anharmonic level using the B3LYP density functional method with a cc-pVTZ basis set.

• Research Organization: Pacific Northwest National Lab. (PNNL), Richland, WA (United States). Environmental Molecular Sciences Lab. (EMSL)
• Sponsoring Organization: USDOE
• DOE Contract Number: AC05-76RL01830
• OSTI ID: 989432
• Report Number(s): PNNL-SA-72086; 32692; KP1704020; TRN: US201019%%487
• Journal Information: Journal of Molecular Spectroscopy, Vol. 262, Issue 1; ISSN 0022-2852
• Publisher: Elsevier
• Country of Publication: United States
• Language: English

Related Subjects

74 ATOMIC AND MOLECULAR PHYSICS
DENSITY FUNCTIONAL METHOD
GROUND STATES
INFRARED SPECTRA
ORIGIN
RESOLUTION
Bicyclopentane High-resolution infrared spectrum Ground state structure and rotational constants Ab initio DFT study Anharmonic frequencies
Environmental Molecular Sciences Laboratory