Calculated rotational strengths and dissymmetry factors for rotational transitions of the chiral deuterated oxiranes, methyl- and dimethyl-oxirane, and methylthiirane

Circular Dichroism at Microwave Frequencies: Calculated Rotational Strengths for Transitions Up toJ= 10 for Some Oxirane Derivatives

“…In previous work, calculations of rotational strengths were reported for the eighteen transitions between the eight simplest asymmetric rotor rotational states for the molecules NHDT, PHDT, the three chiral deuterated oxiranes (7), methyl-and dimethyloxirane, and methylthiirane (8). We report here the results of calculations up to J ϭ 10 in the spectral range from near 3 GHz to near 26 GHz for the three chiral deuterated oxiranes, methyl-and dimethyloxirane, and methylthiirane.…”

“…S. G. Kukolich for many helpful discussions, M. Barfield for helpful ab initio calculations on most of the molecules discussed here, and P. L. Polavarapu for the molecular g-tensor calculations on methylthiirane and the methyloxiranes and for providing additional information on these molecules not included in Ref. (8). Special thanks to Dr. H. Pickett for providing the source code for the CALCAT suite of programs and for permission to modify the code for the calculation of rotational strengths.…”

Chiral Rotational Spectroscopy

“…Let us conclude this section now with a discussion of other phenomena and techniques centered upon the rotational degrees of freedom of chiral molecules, by way of comparison with chiral rotational spectroscopy. Microwave optical rotation and circular dichroism have been considered in theory [71][72][73][74][75][76][77][78][79][80][81]. These phenomena promise chirally sensitive information about a molecule's permanent electric dipole moment and rotational g tensor but are anticipated to be weak, owing primarily to the smallness of molecules relative to the twist inherent to circularly polarized microwaves.…”

On enhanced sensing of chiral molecules in optical cavities

“…Our results imply that the effects of the duality breaking of the molecules on the response of helicity-preserving optical cavities are less pronounced for electronic CD and more pronounced for rotational CD, with vibrational CD lying in the middle. This statement follows from the connection between duality symmetry breaking and Kuhn's dissymmetry factor, and the known scaling of g for each kind of CD: The largest values of g in electronic, vibrational, and rotational CD spectroscopy are of the order 10 À1 , 10 À3 , and 10 À15 , respectively, [68][69][70] and the typical values are at least an order of magnitude lower in each case. The rest of the article is organized as follows.…”