On the spin-rotation contribution to nuclear spin conversion in C_3v-symmetry molecules. Application to CH₃F

Abstract

The symmetrized contribution of E-type spin-rotation interaction to conversion between spin modifications of E-and A 1 -types in molecules with C 3vsymmetry is considered. Using the high-J descending of collisional broadening for accidental rotational resonances between these spin modifications, it was possible to co-ordinate the theoretical description of the conversion with (updated) experimental data for two carbon-substituted isotopes of fluoromethane. As a result, both E-type spin-rotation constants are obtained. They are roughly one and a half times more than the corresponding constants for (deutero)methane. PACS numbers: 31.30.Gs, 33.50.-j Typeset using REVT E X * Electronic address: fractal@iae.nsk.su 12 γ (P ) = 35.3(31) µHz/Torr (1) and 13 γ (P ) = 1942(95) µHz/Torr.It may be compared with the P -normalized collisional broadening (halfwidth) of rotational lines Γ (P )

Nuclear spin conversion in the gaseous phase in the presence of a static electric field: Intramolecular magnetic interactions and the role of collisions

“…In a theoretical work, Gus'kov [19] introduced the role of the spin-rotation interaction in the model. Considering only spin-spin interactions for the two pairs and assuming experimental values for the relaxation rates [20] of ⌫ 1 = 1.09ϫ 10 8 s −1 / Torr and ⌫ 2 = 1.00ϫ 10 8 s −1 / Torr, a calculated value was found to represent only 40 % of the experimental nuclear spin conversion rate in 13 CH 3 F. Therefore, the author assigned the remaining part to a spin-rotation interaction strength of 2.12 kHz, qualitatively compatible with our value.…”

Nuclear spin conversion in formaldehyde

“…Solution for the latter can be found in [22,20,23], which allows to express the strength of mixing in formaldehyde bŷ…”

Sub-collision hyperfine structure of nonlinear-optical resonance with field scanning

“…The Doppler broadening of these components will further show in (8). The next component (ω 3 P (6) F (1) 2(−) ) belongs to 13 CH 4 isotope and is detuned on −0.9 GHza from basic one.…”

“…The shape of the spectrum is defined by ratio of spin-rotation constants [8], and also nuclear spin and rotation g-factor ( [48] and [26], respectively). For our estimations it is possible to suppose Using formula (65a) witĥ…”

“…For the first molecule all hyperfine (spin-rotation) constants can be spectrally determined, but for the second one they can be only partially determined from the spectra. Here to the aid there come researches of spin conversion in molecules [6,7,8]. These additional researches open a possibility of the determination of those hyperfine constants, which do not usually completely affect the spectra.…”