8. Chemical Trapping 4200 C. Atom Activation 4200 1. Photolysis 4200 2. Discharge Methods 4201 3. Laser Ablation 4201 4. Chemical Methods 4201 5. Thermal Activation 4201 D. Apparatus 4202 1. Matrix Isolation 4202 2. Gas-Phase Studies 4202 III. Reaction Pathways 4202 A. Simple Addition Reactions 4204 B. Insertion 4205 C. Isomerization 4207 D. Decomposition 4208 IV. Comparison between Gas-Phase and Matrix Isolation Studies 4210

Reactions of Ground State and Electronically Excited Atoms of Main Group Elements: a Matrix Perspective

Absorption spectra from 2200 to 4000 A have been obtained of chromium, manganese, iron, cobalt, copper, nickel, tin, and palladium atoms trapped in argon matrices at 4.2°K and of iron and copper in krypton and xenon matrices at 4.2 and 20°K. Observed transitions were found to correlate with gas phase transitions, under the assumption of a matrix and atomic configuration dependent shift of the atomic transitions. Energy shifts of the transitions were inversely proportional to matrix atom size. Configurations with an odd number of 3d electrons were shifted less than those with an even number. Within a given configuration, the transitions at higher energies were shifted more than those at lower energies. A Lennard‐Jones potential was unsuccessful in generating the observed energy shifts caused by the interaction between the trapped atom and the matrix. Atom diffusion and resultant aggregation within the matrix both during the condensation of the solid from the gas phase and during warming was found to be a s...

Ultraviolet Absorption Spectra of Transition Metal Atoms in Rare-Gas Matrices.

Optical absorption spectra of Na/Ar systems are calculated by combining the classical Monte Carlo simulation method with a quantum mechanical first‐order perturbation scheme [Balling and Wright, J. Chem. Phys. 79, 2941 (1983)] for estimating the energies of the Na* 3p(2P) excited states. The model incorporates many drastic approximations, but contains no adjustable parameters. Our Na/Ar matrix simulations generated relaxed structures for several candidate trapping sites based on various sized vacancies in face‐centered‐cubic (fcc) solid Ar. Trapping sites for which the equilibrium structures belong to the Oh or Td point groups yielded the experimentally well‐known ‘‘triplet’’ absorption line shape; for these cases, the splitting of the degeneracy of the excited Na* 3p(2P) state is due solely to fluctuations away from the equilibrium structures. Simulations of Na/Ar clusters, surfaces, and matrix sites possessing a strong permanent axial asymmetry yielded a widely split ‘‘doublet plus singlet’’ absorption ...

Monte Carlo simulations of the structures and optical absorption spectra of Na atoms in Ar clusters, surfaces, and solids

Results of experiments on lithium doped rare gas solids (Ar, Kr, and Xe) prepared by laser ablation of solid lithium are presented, including near UV–visible absorption spectra, and photobleaching and annealing studies of the matrices, as well as visible emission spectra of the laser ablated Li plume. The UV–visible absorption spectra of Li/Ar and Li/Kr matrices generated by cocondensing the rare gas and laser ablated Li atoms at 12 K are dominated by a ‘‘blue‐shifted triplet’’ absorption not observed in previously published studies. Control experiments on Li/Ar and Li/Kr matrices generated using a Knudsen oven as the Li atom source showed exclusively an ‘‘unshifted triplet’’ absorption, in agreement with previous studies. The new absorption features are attributed to Li atoms trapped in novel sites in the Ar and Kr solids; sites not accessible to Li atoms generated by the conventional Knudsen effusion technique. Spectra of Li/Xe samples prepared by the laser ablation method showed exclusively the unshift...

Matrix isolation spectroscopy of metal atoms generated by laser ablation. I, The Li/Ar, Li/Kr, and Li/Xe systems

In this paper we present the results of an experimental study of the absorption spectrum of benzene and deuterated benzenes in solid Ar, Kr, Xe, and N2 in the spectral region 2800–1700 A, with special reference to the 2100‐ and to the 1850‐A transitions. Our main results are:(a) On the basis of the observed vibrational structure the second excited singlet state of the benzene molecule is assigned to the 1A1g → 1B1u rather than to the 1A1g → 1E2g excitation.(b) Theoretical calculations of the dynamic electronic–vibrational coupling between the 1B1u and the 1E1u states support the 1B1u assignment of the 2100‐A transition.(c) The vibrational structure of the 1850‐A 1A1g → 1E1u transition was resolved.(d) No experimental evidence for Jahn–Teller coupling in the π → π* 1E1u state was observed, in agreement with theoretical analysis.(e) Information on site splittings for the higher π → π* excitation of benzene in rare‐gas solids has accumulated.(f) Analysis of matrix shifts for the 1A1g → 1B1u and 1A1g → 1E1u t...

C.E. Blount

Papers

Absorption spectra of metal atoms in solid xenon

Temperature dependence of the matrix isolation spectrum of benzene

The near ultraviolet spectra of benzene in inert solids

Temperature dependence of the vacuum ultraviolet spectrum of solid xenon

Spectra of mercury in inert solids