Microwave Spectrum, Structure, and Dipole Moment of Propane

Abstract

The microwave spectrum of ordinary propane and five isotopic species have been measured and analyzed. The rotational constants of C3H8 are 29 207.36, 8446.07, and 7458.98 Mc, and the dipole moment is 0.083±0.001D. In its equilibrium configuration the molecule has C2v symmetry, with both CH3 groups staggered with respect to the CH2 group. The complete structure has been determined by the substitution method. Important parameters are: r(CC)=1.526±0.002 A, ≰CCC=112.4°±0.2°; in the CH2 group, r(CH)=1.096±0.002 A, ≰HCH=106.1°±0.2°; in the CH3 groups, r(CH)=1.091±0.010 A, ≰HCH=107.7°±1.0°. The influence of zero-point effects on the structure determination is discussed; these are found to be particularly bad for the CH3 group, probably because of its large vibrational amplitude.

Dielectric constant of n-hexane as a function of temperature, pressure, and density

“…If the observed difference of 0.050 ± 0.007 em 3/mol in the CM between -50 and 25 °c is considered to result from a /L2/3kT term [17], an effective dipole moment of 0.085 ± 0.006 D (1 debye = 10-12 cgs units)5 is calculated. This is comparable to mo--ments observed in other hydrocarbons [15]. It is doubtful that it is due to impurities, especially water, !> The error indicated is the computed standard deviation.…”

Studies of electron collisions with polyatomic molecules using distributed-memory parallel computers

“…[30][31][32][33][34] No detailed study was made of the basis set dependence of the results; however, a larger basis set was tested for C 2 HI> and found to make little difference. Similar basis sets gave con verged results in previous studies 13.20 on SiH 4 and CH 4 , where it was also possible to compare to results obtained in larger bases.…”

Terahertz vibration-rotation-tunneling spectroscopy of the propane–water dimer: The ortho-state of a 20 cm−1 torsion

“…The A rotational constant of the ortho-propane-water dimer ground state was determined to be 8442.152 (62) MHz, whereas the B rotational constant of free propane was reported as 8446.07 MHz [19]. The fact that these two constants are so close indicates that the a inertial axis of the dimer is approximately aligned with the b inertial axis of the free propane molecule.…”