Oxetane is a four-membered ring molecule exhibiting a large-amplitude ring-puckering motion. In order to analyze this vibration we recorded a rotationally resolved far-infrared spectrum between 50 and 145 cm(-1). The analysis of the ring-puckering fundamental band with the assignment of 1108 lines, has been presented in a previous paper. In the present work we present a list of further 6531 assigned transitions between the five lowest excited ring-puckering states. The 4983 term values involved in the transitions assigned in this and in the preceding work have been evaluated by the "Ritz" program, and are now available. An A-reduced Watson Hamiltonian in any of the three representations I-r, IIr, and IIIr was used to perform a fit of the assigned transitions. Precise rotational constants and quartic as well as a full set of sextic centrifugal distortion constants were obtained for the investigated ring-puckering states. For the first time, high-resolution values for the vibrational G(v) parameters have been obtained, and we have added terms in x(6) and x(8) to the double minimum-potential well describing the ring-puckering motion, in order to reproduce their values within the experimental accuracy. The same potential still reproduces the lower resolution values of the Q-branch origins involving higher ring-puckering states up to nu(rp) = 14 found in the previous literature. (C) 2003 Elsevier Science (USA). All rights reserved.
|Autori interni:||MORUZZI, GIOVANNI|
|Autori:||Moruzzi G; Kunzmann M; Winnewisser BP; Winnewisser M|
|Titolo:||Ritz assignment and Watson fits of the high-resolution ring-puckering spectrum of oxetane|
|Anno del prodotto:||2003|
|Digital Object Identifier (DOI):||10.1016/S0022-2852(03)00021-3|
|Appare nelle tipologie:||1.1 Articolo in rivista|