Shpolskii matrix

The effect was first described by Eduard Shpolskii in the 1950s[1] and 1960's[2][3][4] in the journals Transactions of the U.S.S.R. Academy of Sciences and Soviet Physics Uspekhi.

Subsequent detailed studies of concentration and speed of cooling behavior of Shpolskii systems by L. A. Nakhimovsky and coauthors led to a hypothesis that these systems are metastable segregational solid solutions formed when one or more chromophores replace two or more molecules in the host crystalline lattice.

[5][6] Isothermic annealing of the supersaturated rapidly frozen solutions of dibenzofuran in heptane was performed, and it was shown that the return of the metastable system to equilibrium in time reasonable for laboratory observation required the annealing temperature to be close to the melting temperature of the metastable frozen solution.

Low molecular weight normal alkanes absorb light at energies higher than the absorption of all pi-pi electronic transitions of aromatic hydrocarbons.

The length of the alkanes is often chosen to approximately match at least one of the dimensions of the chromophore, and are usually in the size range between n-pentane and n-dodecane.

Figure 1. Absorption spectrum of dimethyl-s-tetrazene in n-heptane at 4.2 K. The sharp lines are characteristic of Shpolskii matrix spectra. Data adapted from Gebhardt et al. 10