Stephen J. Harris

Determination of the structure of ArHCl

The radio frequency and microwave spectra of K = 0 states of ArHCl and ArDCl have been measured by molecular beam electric resonance spectroscopy. The rotational and hyperfine structure constants for the lowest vibrational state of the four isotopic species are ArH35u2009ClArD35u2009ClB = (B+C)/2 = 1.678511 (5)GHzB − 2DJ = 1.657596 (10)GHzDJ=20.33 (20)kHz(eqQ)aC1 = −36.250 (20)MHz(eqQ)a=−23.027(10)MHz(eqQ)aD = +102.3 (50)kHzμa=0.81144(10)Dμa=1.00355(70)D ArH37u2009ClArD37u2009ClB − 2DJ = 1.631566 (5)GHzB − 2DJ = 1.611876 (10)GHz Only the lowest vibrational state has been observed. The molecule is extremely nonrigid. The average Ar–Cl distance is 4.006 A in ArHCl and 4.025 A in ArDCl. The Ar–Cl–H angle is acute and the amplitude of the zero point angle bending is extremely large. The average Ar–Cl–H angle is near 45°, while the average Ar–Cl–D angle is near 34°. The vibrational frequency of Ar–HCl bond stretching is computed to be 32.2 cm−1 from the observed centrifugal distortion constant.

Benzene dimer: A polar molecule

The electric deflection of molecular beams of (C6H6)2, produced by adiabatic expansion, has been measured. The benzene dimer is observed to be a polar species. It is likely that the structure of this species is that of two perpendicular planes, as is observed for nearest neighbors in crystal and liquid benzene.

Intermolecular potential between an atom and a diatomic molecule: The structure of ArCIF

Author Institution: Department of Chemistry, Harvard University; Bell Laboratories, Harvard University

Determination of the structure of ArHF

Radio‐frequency and microwave spectra of K = 0 states of ArHF in the ground vibrational state have been measured by molecular beam electric resonance spectroscopy. The rotational constant is (B+C)/2=3065.719 MHz; the component of the dipole moment along the a inertial axis is μa = 1.332 D. From the centrifugal distortion constant, DJ = 72.1 kHz, the stretching frequency of the van der Waals bond is estimated to be 42.1 cm−1. In analogy with ArHCl the internal Ar–F–H angle θ is expected to be acute and the average value of the angle is 48.20°. The equilibrium configuration is likely to be near linear with atomic arrangement ArHF. The vibrationally averaged Ar–F distance is 3.540 A.

Intermolecular potential between an atom and a linear molecule: The structure of ArOCS

The radio frequency and microwave spectrum of ArOCS has been measured by molecular beam electric resonance spectroscopy. ArOCS is a prolate, slightly asymmetric top. The rotational constants and dipole moment components of the ground vibrational state are as follows: Au2009=u20096786.014(20) MHz, Bu2009=u20091509.909(6) MHz, Cu2009=u20091227.220(6) MHz, μau2009=u20090.2146(10) D, μbu2009=u20090.669(2) D. The complex has a nonlinear, T‐shaped structure and the vibrationally averaged distances are Ar–Cu2009=u20093.578(1), Ar–Ou2009=u20093.601(1), and Ar–Su2009=u20094.101 A. The observed structure is analogous to isoelectronic and isovalent chemically bound systems, and it is shown to be that expected from an interaction of the highest occupied orbital of Ar with the lowest unoccupied orbital of OCS.