Relative Intensity Measurements in Microwave Spectroscopy

Abstract

ABSTRACT9 I' A method is described for the measurement of peak intensity ratios of gas phase microwave absorption lines.Large errors associated with multiple reflections in the waveguide have been eliminated by careful design and the use of ferrite isolators.Detector nonlinearities have been neutralized by using a precisely ___ • calibrated step attenuator allowing both lines involved in a ratio to be displayed with approximately the same amplitude.Means of minimizing add tional sources of error are discussed. CnApplication of the method to a number of problems indicates that ratios accurate to a few percent can be obtained.

The Rotational Spectrum of Monothioformic Acid. III. Dipole Moment and Relative Intensity Measurements1,2

“…The relative intensity of two absorption lines due to the same rotational transition in the two different rotamers of HC(:0)SH is given by 5 where the subscripts c and t denote eis and trans respectively and:…”

“…with the implicit assumption that the equilibrium Jrans-HC(:0)SH ^ czs-HC (:0) SH (5) had been established. The average of the AE values reported in Table V …”

“…There have also been a number of attempts to determine the energy difference between the ground states of rotational isomers by microwave relative intensity measurements 3 ' 4 . Although the uncertainty in the measured energy differences has usually been rather large, the gradual development of more sophisticated microwave spectrometer systems has now made accurate relative intensity measurements feasible [5][6][7] .…”

Conformational Preference of 2‐(Halomethyl)‐ and 2‐(Oxymethyl)Pyridines: Microwave Spectrum, Ab Initio, and MM3 Studies of 2‐(Fluoromethyl)Pyridine

“…Relative intensity measurements performed largely as described in ref. [19] with carefully selected lines of the ground and first excited state yielded 53(15) cm-' for the torsional fundamental. This is close to the 57 cm-' that was predicted in the MP2/6-31 G** computations (not given in Table 1).…”

Microwave Spectra of Furazan. IV. Rotation Spectra of Vibrationally Excited States of Perdeuterated Furazan

“…= odd even odd 4 5 summarised in Table 2. As in the case of normal furazan, relative intensity comparisons [5] between rotationally even and odd transitions within a particular satellite spectrum will therefore allow the determination of the symmetric or antisymmetric nature of the vibrational mode excited. As before [la], the sign of the inertia defect contribution Ö(ID) permits a tentative subdivision of the excited states into "in-plane" (A t .…”