Anomalous hyperfine structure of NSF{sub 3} in the degenerate vibrational state v{sub 5}=1: Lifting of the parity degeneracy by the fluorine spin-rotation interaction

Journal Article · Mon Mar 15 00:00:00 EDT 2010 · Physical Review. A

DOI:https://doi.org/10.1103/PHYSREVA.81.032518· OSTI ID:21408424

Harder, Hauke; Macholl, Sven; Maeder, Heinrich; Fusina, Luciano; Ozier, Irving ^[1]

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1. Institut fuer Physikalische Chemie, Universitaet Kiel, Olshausenstr. 40-60, DE-24098 Kiel (Germany)

For the principal isotopologue {sup 14}N{sup 32}S{sup 19}F{sub 3} of thiazyl trifluoride in the degenerate fundamental state (v{sub 5}=1), the hyperfine structure has been investigated in the Q-branch spectrum between 8 and 26.5 GHz using microwave Fourier transform waveguide spectrometers with a resolution limit of {approx_equal}30 kHz. In addition to l-type doubling spectra and l-type resonance transitions with ({Delta}k={Delta}l={+-}2), perturbation-allowed spectra were measured with {Delta}(k-l)={+-}3,{+-}6. The range in J was from 13 to 61; for the lower states, kl=-3,-2,-1,0,+1. For all the transitions, the hyperfine patterns observed are predicted to be doublets when only the nitrogen quadrupole Hamiltonian H{sub Q}{sup N} is taken into account. Doublets were indeed measured for transitions with {Gamma}{sub RV}=A{sub 1{r_reversible}}A{sub 2}, where {Gamma}{sub RV} is the rovibrational symmetry. However, when {Gamma}{sub RV}=E{r_reversible}E, triplets and quartets were observed in addition to doublets. These anomalous hyperfine patterns are shown to be due to the ({Delta}k={+-}1) and ({Delta}k={+-}2) matrix elements of the fluorine spin-rotation Hamiltonian H{sub SR}{sup F} characterized by the fluorine spin-rotation constants c(1)=(1/2)(c{sub xz}+c{sub zx}{sup *}) and c(2)=(1/2)(c{sub xx}-c{sub yy}), respectively. These terms in H{sub SR}{sup F} lift the parity degeneracy for {Gamma}{sub RV}=E. The rovibrational Hamiltonian H{sub RV} was adopted from an earlier partner study [S. Macholl et al., J. Phys. Chem. A 113, 668 (2009)]. A good fit to the hyperfine data was obtained with a standard deviation of 3.1 kHz. In the fitting process, 12 rovibrational parameters were varied, while the remaining constants in H{sub RV} were left at the values of Macholl et al. In addition, six hyperfine parameters were determined: four in H{sub Q}{sup N}, and two in H{sub SR}{sup F}. It was found that |c(1)|=7.48(24) kHz and |c(2)|=2.423(22) kHz. This determination of c(1) is the first to be reported based on frequency measurements. In all the previous detections of parity doubling where the splittings were accounted for quantitatively, the levels involved had K=|k|=1 in studies of the ground vibrational state or G{identical_to}|k-l|=1 in investigations of degenerate vibrational states. In the current work, several different values of G were involved, thus demonstrating experimentally for the first time that this splitting process is a general phenomenon. The key to the observation of the parity doubling lies in the regional resonances discovered by Macholl et al. The clustering of rovibrational levels at low K leads to severe mixing. For each eigenstate involved in a regional resonance, the eigenstate consists of a linear superposition of basis vectors with several different values of kl having sizable expansion coefficients. As a result, the ({Delta}k={+-}1,{+-}2) matrix elements of H{sub SR}{sup F} that typically connect levels widely separated in energy occur here effectively on the diagonal, thereby greatly enhancing the effects of c(1) and c(2). These spin-rotation matrix elements are derived here for {Gamma}{sub RV}=E in the low-field representation.

• OSTI ID: 21408424
• Journal Information: Physical Review. A, Vol. 81, Issue 3; Other Information: DOI: 10.1103/PhysRevA.81.032518; (c) 2010 The American Physical Society; ISSN 1050-2947
• Country of Publication: United States
• Language: English

Related Subjects

74 ATOMIC AND MOLECULAR PHYSICS
FLUORINE
FOURIER TRANSFORMATION
FREQUENCY MEASUREMENT
GHZ RANGE 01-100
HAMILTONIANS
HYPERFINE STRUCTURE
KHZ RANGE 01-100
MATRIX ELEMENTS
MICROWAVE RADIATION
PARITY
RESOLUTION
SPECTRA
SPECTROMETERS
SPIN
TRIPLETS
VIBRATIONAL STATES
ANGULAR MOMENTUM
ELECTROMAGNETIC RADIATION
ELEMENTS
ENERGY LEVELS
EXCITED STATES
FREQUENCY RANGE
GHZ RANGE
HALOGENS
INTEGRAL TRANSFORMATIONS
KHZ RANGE
MATHEMATICAL OPERATORS
MEASURING INSTRUMENTS
MULTIPLETS
NONMETALS
PARTICLE PROPERTIES
QUANTUM OPERATORS
RADIATIONS
TRANSFORMATIONS