Journal of Physical Chemistry A, Vol.102, No.37, 7233-7240, 1998
Electronic band systems of SF2 radicals observed by resonance-enhanced multiphoton ionization
A pulsed de electric discharge in a pulsed supersonic beam has been used as an efficient source of producing radicals. The (2+1) REMPI spectra of the SF2 radicals were investigated between 245 and 365 nm (54945-81630 cm(-1)). Eight electronic band systems have been observed in this range. One series with quantum defect delta = 1.961(6) is comprised of the (B) over tilde B-1(1)(4s) and (J) over tilde B-1(1)(5s) Rydberg states which have origins at nu(0-0) = 54470 and 68951 cm(-1), respectively. Vibrational analyses of these Rydberg states showed that in the B B-1(1)(4s) state omega(1)'(a(1) sym str) = 981(23) cm(-1) and in the (J) over tilde B-1(1) (5s) state omega(1)'(a(1) sym str) = 942(3) cm(-1). A second Rydberg series (E) over tilde (4p) with quantum defect delta = 1.61 is characterized with the spectroscopic values nu(0-0) = 62025 cm(-1), omega(1)'(a(1) sym str) = 941(27) cm(-1), and omega(2)'(a(1), bend) = 413 (12) cm(-1). Incompletely rotational analysis revealed that the (F) over tilde electronic state with nu(0-0) 63812 cm(-1), omega(1)'(a(1) sym str) = 966(6) cm(-1), and omega(2)'(a(1), bend) = 417(23) cm(-1) merges with the vibrational progression of the (E) over tilde (4p) state. The (F) over tilde state might be a 4p Rydberg state of another hybrid symmetry with the quantum defect delta = 1.50. A third Rydberg series is comprised of the (G) over tilde (3d) (nu(0-0) = 68378 cm(-1), omega(1)' = 939(12) cm(-1), delta = 0.086), the (H) over tilde (3d) (nu(0-0) = 68571 cm(-1), omega(1)' = 936(4) cm(-1), delta = 0.064), and the (I) over tilde (3d) (nu(0-0) = 68847 cm(-1), omega(1)' = 933(4) cm(-1), delta = 0.032). In addition, two valence states labeled as the (B) over tilde' state (38623 cm(-1)) and (C) over tilde state (56219-61278 cm(-1)) were also observed. A fit of the Rydberg formula to the ns(B-1(1)) (n = 4,5) origins found the adiabatic ionization potential of SF2 radicals to be IFa = 10.021(1) eV.
Keywords:INFRARED-SPECTRUM, SULFUR DIFLUORIDE, RYDBERG STATES;SUPERSONIC JET, SPECTROSCOPY, FLUORIDES, PRODUCTS, CF