Rotational spectrum of and : completely resolved nuclear hyperfine structures due to and (original) (raw)
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Laboratory Measurements of the Hyperfine Structure of H 14 N 12 C and D 14 N 12 C
The Astrophysical Journal, 2006
The nuclear quadrupole hyperfine structure of H 14 N 12 C and D 14 N 12 C has been resolved in the laboratory for the first time using millimeter-wave absorption spectroscopy. The transient species were produced in a pulsed DC discharge nozzle, and Doppler broadening effects were minimized by propagating the millimeter waves coaxially with the supersonic molecular beam. New rest frequencies for the , , and J p 1-0 J p 2-1 J p 3-2 rotational transitions of the ground vibrational state were determined. The nuclear quadrupole coupling constants derived from the spectra are kHz for H 14 N 12 C and kHz and (eQq) p 264.5 ע 4.6 (eQq) p 294.7 ע 13.
Journal of Molecular Structure, 2006
The rotational spectrum of 13 C 1 methyl formate (H 13 COOCH 3 ) has been observed in the frequency range 7-610 GHz. Two hundred and ninety one transitions up to JZ58 (K max Z24) were assigned to the A-species of the ground torsional state. They could be fitted to a standard Watsonian involving 19 parameters (up to one decic centrifugal distortion constant). About 260 E-transitions were also assigned. A global analysis of all these transitions using the internal axis method gave a satisfactory fit permitting to determine the three internal rotation parameters (I a Z 3.132(4) mÅ 2 , V 3 Z4912(6) J/mol and :(i,a)Z52.30(5)8, which is the angle between the principal axis a and the internal rotation axis i) and allowing us to make an accurate prediction of the rotational spectrum. q
Rotational spectroscopy, dipole moment and 14N nuclear hyperfine structure of iso-propyl cyanide
Journal of Molecular Spectroscopy, 2011
Rotational transitions of iso-propyl cyanide, (CH3)2CHCN, also known as iso-butyronitrile, were recorded using long-path absorption spectroscopy in selected regions between 37 and 600GHz. Further measurements were carried out between 6 and 20GHz employing Fourier transform microwave (FTMW) spectroscopy on a pulsed molecular supersonic jet. The observed transitions reach J and Ka quantum numbers of 103 and 59, respectively, and yield
Precise Laboratory Frequencies for the J = 1-0 and J = 2-1 Rotational Transitions of C18O
Astrophysical Journal, 2003
Precise rest frequencies for the and rotational transitions of C 18 O have been measured in J p 1-0 J p 2-1 the laboratory using the Lamb-dip technique with an accuracy better than 1 kHz (2 j uncertainty). In contrast to the main CO isotopomer, interstellar C 18 O lines are significantly narrower and very often have Gaussian line shapes. Taking into account their relatively high intensities in interstellar clouds, the new laboratory measurements allow us to consider C 18 O as the best frequency standard in radio astronomical spectroscopy.
Rotational spectra of mono-substituted asymmetric C< sub> 6 H< sub> 6–H< sub> 2 O dimers
2005
This paper reports the assignment of the rotational spectra of the m = 0 and 1 states of 13 CC 5 H 6-H 2 O and C 6 H 5 D-H 2 O dimers. The m = 1 progression was not identified or assigned for both 13 CC 5 H 6-H 2 O and C 6 H 5 D-H 2 O in the earlier work, though for the symmetric isotopomers (C 6 H 6-H 2 O/D 2 O/H 2 18 O), they were identified [H.S. Gutowsky, T. Emilsson, E. Arunan, J. Chem. Phys. 99 (1993) 4883]. The m = 1 transitions for 13 CC 5 H 6-H 2 O and C 6 H 5 D-H 2 O were split into two, unlike that of the parent C 6 H 6-H 2 O isotopomer. The splitting varied, somewhat randomly, with quantum numbers J and K. The m = 0 lines of 13 CC 5 H 6-H 2 O had significant overlap with the m = 1 lines of the parent isotopomer, clouding proper assignment, and leading to an rms deviation of about 200 kHz in the earlier work. The general semi-rigid molecular Hamiltonian coupled to an internal rotor, described recently by Duan et al. [Y.B. Duan, H.M. Zhang, K. Takagi, J. Chem. Phys. 104 (1996) 3914], is used in this work to assign both m = 0 and 1 states of 13 CC 5 H 6-H 2 O and C 6 H 5 D-H 2 O dimers. Consequently, the m = 0 fits for 13 CC 5 H 6-H 2 O/D 2 O have an rms deviation of only 4/ 7 kHz, comparable to experimental uncertainties. The fits for m = 1 transitions for 13 CC 5 H 6-H 2 O and C 6 H 5 D-H 2 O dimers have an rms deviation of about 200 kHz. However, it is of the same order of magnitude as that of the m = 1 state of the parent C 6 H 6-H 2 O dimer. The A rotational constants determined from the m = 0 fits for both 13 CC 5 H 6-H 2 O and 13 CC 5 H 6-D 2 O isotopomers are identical and very close to the C rotational constant for 13 CC 5 H 6. This provides a direct experimental determination for the C rotational constant of 13 CC 5 H 6 , which has a negligible dipole moment.
Organic magnetic resonance, 1978
The 13C-'3C spin-spin coupling constants in natural abundance oxetane, thietane, cydobutanone, bromoand chlorocydobutane have been measured. Furthermore, the I3C isotope-induced changes in the chemical shifts of the different "C nuclei in the molecules mentioned above are reported. These shifts are normally to higher magnetic field; in cydobutanone, however, the resonance of the carbonyl carbon has shifted to lower field because of the substitution of "C-3 for "C-3.