Articles you may be interested inA study of the structure and dynamics of the hydronium ion by high resolution infrared laser spectroscopy. III. The ν3 band of D3O+ J. Chem. Phys. 92, 3257 (1990); 10.1063/1.457884 Observation of forbidden transitions of ammonium ion (NH+ 4) ν3 band and determination of ground state rotational constants. Observation of ν3 band allowed transitions of ND+ 4 A study of the ν1 fundamental and bendexcited hot band of DNN+ by velocity modulation absorption spectroscopy with an infrared difference frequency laser J. Chem. Phys. 81, 5281 (1984); 10.1063/1.447670 Velocity modulation infrared laser spectroscopy of molecular ions: The ν1 and ν3 bands of fluoronium (H2F+)Over 200 transitions in the V3 band of the ammonium ion (NH4+) have been measured near 3 f./,m with a color center laser spectrometer to an accuracy of 0.005 cm -I using the technique of velocity modulation laser absorption spectroscopy. These have been assigned to strongly allowed QO, P + and Rbranches in the triply degenerate asymmetric stretching mode of a spherical top molecule, and analyzed by nonlinear least-squares methods with an effective sixth order Hamiltonian. Ground state constants were fixed at values obtained with a recent ab initio molecular potential surface. Twenty-six molecular parameters were determined in the fit. The fact that terms in the Hamiltonian beyond fourth order are required to fit transitions with J as low as 12 indicates the existence of a perturbation involving the V3 = 1 levels. It is suggested that a Fermi resonance between V3 and V 2 + V 4 is an important source of this perturbation, as in the case of CH 4 . The frequencies of "forbidden" transitions, required in order to determine the ground state parameters, are predicted to high accuracy with these new constants.

Abstracta-type rotational transitions of molecules in the vibrational ground state of thioketene, HA = 286 655(82) MHz,B = 5 659.47596(72) MHz,C = 5 544.51269(72) MHz.A detailed centrifugal distortion analysis by means of Watson's S-reduced Hamiltonian led to the determination of four quartic, two sextic and two higher order distortion constants:DDDdEffective rotational and centrifugal distortion constants using planarity conditions were calculated. The electric dipole moment of thioketene was determined to be μ = 1.01(3) D.

Velocity modulation infrared laser spectroscopy and structure of the amide anion (NH− 2 ) J. Chem. Phys. 85, 4222 (1986); 10.1063/1.451792 Velocity modulation laser spectroscopy of negative ions: The infrared spectrum of hydroxide (OH−) J. Chem. Phys. 84, 5308 (1986); 10.1063/1.449941 Determination of the equilibrium structure of protonated nitrogen by high resolution infrared laser spectroscopy J. Chem. Phys. 84, 605 (1986); 10.1063/1.450607 Velocity modulation infrared laser spectroscopy of molecular ions: The ν1 and ν3 bands of fluoronium (H2F+)The gas phase infrared spectrum ofthe fluoronium ion (H 2 F+) was recorded with Dopplerlimited resolution between 3080 and 3520 cm -I by velocity modulation laser absorption spectroscopy of a hydrogen plasma containing 5% HF. One hundred and nine of the observed transitions were assigned to the symmetric stretch ('I'd and 217 to the asymmetric ('113) stretch. A least squares analysis of '113 transitions up to J = 11 and Ka = 6 and VI transitions up to Ka = 4 with Watson's S-reduced Hamiltonian yielded rotational constants and centrifugal distortion constants for the vibronic ground state and for the two excited states. Small Coriolis interactions between VI and '113 levels were observed, but were not treated explicitly. The band origins for '113 and VI are 3334.6895(26) and 3348.7078(36) cm-I, respectively. The ro structure ofH 2 F+ was determined as: r HF = 0.9577 A < HFH = 114.55°. 4 32 -5 33 5 05 -6 06 6«!-625 11 J J r ". If r I I ! 3211.0 3210.0 3209.0 cm-1 PIG. 2. A portion of the P-branch of the V3 band ofH2P+, J.

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The ν3 band of the ammonium ion was measured near 3.0 μm with a color center laser spectrometer using the technique of velocity modulated absorption spectroscopy. NH4+ was produced in an ac discharge containing 0.1 Torr of nH3 and 1.5 Torr of H2. Seventy individual transitions were measured with an accuracy of 1×10−6 and assigned to q0, P+, and R− branches of a tetrahedral molecule. The constants derived in a preliminary analysis are: νeff0=3342.540 2(97) cm−1, B0+B1−2B1χ3=11.110 8(35) cm−1, B1−B0=−0.050 71(45) cm−2u1, and D=8.5(2.6)×10−5 cm−1. (AIP)