High-Resolution FTIR Study of the (ν3+ ν4, ν1+ ν4) Interacting System of Rovibrational Bands of PF3Between 1100 and 1300 cm−1

✍ Scribed by N.Ben Sari-Zizi; H Najib; R Sebihi; P Pracna

• Publisher: Elsevier Science
• Year: 1998
• Tongue: English
• Weight: 363 KB
• Volume: 190
• Category: Article
• ISSN: 0022-2852
• DOI: 10.1006/jmsp.1998.7568

✦ Synopsis

With a resolution of 4.4 1 10 03 cm 01 , we were able to identify in this range the very weak n 2 / 2n 0 4 (A 1 ) component near 1180 cm 01 , the n 3 / n 4 band around 1205 cm 01 with its (A 1 / A 2 ) and E very intermixed components, and the n 1 / n 4 (E) band centered at 1238 cm 01 . Three thousand six hundred transitions belonging to the (n 3 / n 4 , n 1 / n 4 ) interacting system were fitted together with a model taking into account l(2, 2) interactions inside n 1 / n 4 and between (A 1 / A 2 ) and E components of n 3 / n 4 , the l-vibrational resonance inside n 3 / n 4 (A 1 / A 2 ), and the Coriolis interactions between n 1 / n 4 and n 3 / n 4 (A 1 / A 2 ) on one hand and between n 1 / n 4 and n 3 / n 4 (E) on the other. Four available MW transitions were also included in the fit. A rms of 0.76 1 10 03 cm 01 was obtained with 34 free parameters among 38. Normally the Fermi resonance, which links n 3 to n 2 / n 4 with a coupling term W 234 Å 2.86 cm 01 , must connect each component of n 3 / n 4 with each component of n 2 / 2n 4 . But since we have only little experimental information about the weak n 2 / 2n 0 4 component (120 assigned lines) and none about the dark n 2 / 2n {2 4 component, it was not possible to introduce this resonance in the fit. However, the bandcenters' shifts were calculated since the basic coupling term W 234 and the anharmonic constant x 24 are well known. Therefore, according to this approximation, the very sensitive anharmonic constants x 34 and g 34 could be deduced. Of course the x 14 Fermi-independent constant, derived directly from the (n 1 / n 4 ) 0 bandcenter given by the fit, was certainly more accurate.