THE LOW FREQUENCY BROADBAND FOURIER TRANSFORM MICROWAVE SPECTROSCOPY OF HEXAFLUOROPROPYLENE OXIDE, CF$_3$CFOCF$_2$

the John B. Stephenson Fellowship Of Aca Is Gratefully; Shipman, Steven T.; Neill, Justin L.; Lesarri, Alberto; Pate, Brooks H.Author Institution: Department of Natural Sciences, Union College, Barbourville, KY 40906; Department of Chemistry, University of Virginia, McCormick Rd., P.O. Box 400319, Charlottesville, VA 22904; Departmento de Quimica Fisica, Universidad de Valladolid, Facultad de Ciencias, Valladolid, 47005 SPAIN; Department of Chemistry, University of Virginia, McCormick Rd., P.O. Box 400319, Charlottesville, VA 22904The pure rotational spectra of hexafluoropropylene oxide (HFPO), CF$_3$CFOCF$_2$, as well as its $^{13}$C (1.07\%) and $^{18}$O (0.205\%) isotopomers were recorded in natural abundance from 2.0 to 26 GHz. Low frequency transitions (2 - 8 GHz) were measured by a recently designed chirped-pulse Fourier transform microwave (CP-FTMW) spectrometer at the University of Virginia. The observed spectra lines of $^{13}$C isotopomers (in natural abundance) demonstrate the capability and sensitivity of the CP-FTMW spectrometer operating in 2 - 8 GHz region. The spectra in 8.0 - 26 GHz region were recorded by a Fabry-Perot cavity Fourier transform microwave (FP-FTMW) spectrometer. All the five isotopologues of HFPO were found, and their spectroscopic constants were fit from assigned spectral lines using JB95 and Pickett$^{,}$s SPFIT suite of programs. For the dominate HFPO isotopomer: $A_{0}$ = 2217.04887(11) MHz, $B_{0}$ = 1101.48958(5) MHz, $C_{0}$ = 936.60131(5) MHz, $\Delta_{J}$ = 55.0(2) Hz, $\Delta_{JK}$ = 107.5(9) Hz, $\Delta_{K}$ = -20(2) Hz, $\delta_{J}$ = 8.49(6) Hz, and $\delta_{K}$ = -266(2) Hz. The experimentally determined molecular structure and rotational constants are in a good agreement with our density functional theory calculation using B3LYP/6-31g(d) method