Frozen inert gas matrices of N2 and Ar containing 02 and In or Ga atoms have been prepared by matrix isolation techniques and studied by infrared absorption spectroscopy. Analyses of the spectra have shown that these reagents react to produce metal superoxide molecules, M+02", which are similar to those of the alkali and alkaline earth metals. The stretching modes of these species absorb in the regions of 1080-1090 cm"1 for r1(A1), 330-380 cm"1 for * 2( ), and 270-290 cm"1 for ^(Bj). In addition to the superoxides, various aggregate species are produced. One of these has been identified as the superoxide dimer, which apparently has an 02M-M02 structure of I)2d symmetry. Another aggregate has been identified as a rhombic M02M species which is formed by the addition of a metal atom to the superoxide. Small quantities of the suboxide dimer (ln20)2 also were detected in these matrices. The evidence indicates that this species was formed by the addition of an In atom to each oxygen of the In02In(D2ft) species. This dimer is of interest because it is readily formed by aggregation of the suboxide monomer in experiments involving the vaporization of the condensed oxide systems.

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Naphthalene and methyl-and halonaphthalene cations have been produced by one-and two-photon matrix photoionization techniques and trapped in solid argon for absorption spectroscopic study. Five transitions in the visible and ultraviolet regions have been assigned to the radical cations. The argon matrix absorption spectra are in agreement with photoelectron and photodissociation spectra, absorption spectra of the ions in Freon glasses, and simple HMO calculations. Substituent effects were observed for the origins of the five transitions. The repeating vibronic intervals in the red N+ transitions due to the C(9)-C(10) stretching fundamentals for this group of substituted naphthalene cations are 40-50 cm"1 above the Raman fundamentals for the molecules whereas the vibronic intervals due to ring deformation modes are up to 30 cm"1 below the appropriate Raman fundamentals, and vibronic intervals in the sharp UV band are 30-45 cm"1 below Raman fundamentals, which correlate with HMO it bond orders.

The hydrogen-bonded pi complex C 2 H.--HF has been prepared by codeposition of C 2 H. and HF with excess argon at 12 K. Isotopic substitution in both submolecules identified the complex and provided assignments to v, at 3731 cm -I, VI at 424 and 396 cm -', and v, at 973 cm -1. The observation of a substantial perturbation on the out-of-plane bending mode of the C 2 H. submolecule in the complex without a perturbation on the in-plane bending mode indicates that H-F is bonded to the pi electron system perpendicular to the plane of the molecule. The positions of V, and VI indicate a hydrogen bond of intermediate strength and the splitting in VI is characteristic of the anisotropy in the' hydrogen bonding interaction with a 7r system.

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