Study of Impurity–Host Coupling in Shpolskii Matrices

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Abstract
The nature and strength of the impurity–matrix coupling in Shpolskii matrices (frozen normal alkane matrices) have been determined from a study of the absorption linewidth, position, and intensity of several of the vibronic bands of anthracene, naphthalene, coronene, and 1, 12 benzperylene dissolved in their appropriate n‐alkane solvents. At 4°K the half‐intensity linewidths of the first electronic absorption bands are small (2–6 cm−1). In coronene the second absorption band is also narrow at 4°K (4 cm−1). Comparison with a theory originally developed for inorganic impurity–matrix systems yields values for the impurity lattice coupling parameters which are of the same order of magnitude as those found for f‐electron excitations in rare‐earth impurity–matrix systems. Because Shpolskii matrices are weakly interacting host crystals for aromatic solutes, it is possible to study the upper excited states of such solutes as if they were a “dilute cold gas.” The implication of this observation for the study of radiationless processes is indicated.