The microwave spectroscopy of trans-ethyl methyl ether in the first skeletal torsionally excited state

Effective rotational Hamiltonian for molecules with internal rotors: Principles, theory, applications and experiences

“…As a result, all expectation values (matrix elements) of any operator involving the variable s depend periodically on the projection quantum number K. Therefore, the effective rotational Hamiltonian can be set up by using this periodicity without the need to actually solve the internal rotation Hamiltonian similar to the effective or phenomenological Hamiltonians used by Ohashi, Hougen and coworkers. [31][32][33][12][13][14].…”

The microwave spectroscopy of trans-ethyl methyl ether in the ν29=1 excited torsional state

“…To clarify the unassigned lines, which are also useful for astronomical identification, we started a series of the studies on the torsionally excited states. The first skeletal torsionally excited state was reported recently [12]. The present paper is the second in our series of studies for the low-lying torsionally excited states of transethyl methyl ether, and an analysis, including splittings due to the two inequivalent internal rotors, of the m 29 ¼ 1 excited torsional state will be given.…”

“…The torsional barrier heights and the molecular parameters related to the internal rotation splittings were estimated in Evaluations 1 and 2, respectively. In the present discussion, we neglect the interaction scheme involving the skeletal torsionally excited state because the energy difference between O-CH 3 and C-CH 3 torsionally excited states is much smaller, even though it was suggested in the previous study [12] on the skeletal torsionally excited state that the inverted A/E sequence seen in the first skeletal torsionally excited state would be produced by the O-CH 3 torsion-skeletal torsion and C-CH 3 torsion-skeletal torsion interactions.…”

“…(18) are shown together with those obtained in the least squares analysis of the spectrum. The barrier heights including those obtained in the previous studies [6,8,12] are compiled in Table 6. Our barrier heights agree with the IR results [6].…”

CCSD(T) study of the far-infrared spectrum of ethyl methyl ether

“…1 Before this uncertain detection, EME attracted low attention even though the relevance for radioastronomy and the miss at point of the new instruments for detection, as ALMA, have motivated laboratory measures of rotational spectra of many ethers. [3][4][5][6][7][8][9][10][11][12][13] Currently, Fuchs et al 3 recorded the spectrum for the vibrational-torsional ground state assigning and making predictions of line positions up to 450 GHz, extending the previous assigned frequency intervals of Hayashi and Kuwada, 4 Hayashi and Adachi, 5 and Tsunekawa et al 6 Kobayashi et al 7 recorded and analyzed the microwave spectrum in the first skeletal torsionally excited state.…”