Famed Bulgarian physicists. I. St. Petroff's Goettingen research of the photostimulated interconversions of color centers in alkali halides: the discovery of the photostimulated aggregation

TL;DR

This paper reviews the life and groundbreaking research of Bulgarian physicist I. St. Petroff, highlighting his discovery of photostimulated aggregation of color centers in alkali halides during WWII, using optical absorption techniques.

Contribution

It reports the first evidence of a primary photochemical solid-state reaction leading to nanoscale products in alkali halide crystals.

Findings

Discovery of new absorption bands for F center aggregates

Observation of photostimulated interconversions of color centers

Identification of a primary photochemical reaction producing nanoscale products

Abstract

This essay tells briefly of the life and work of one of the most successful scientists originating from a Balkan settlement whose name and popularity have greatly exceeded its realm. The word is of a discovery during WWII of the photostimulated aggregation of the F centers (else alkali atoms) dissolved from the vapor into an alkali halide crystal. Using optical absorption techniques while a grantee of Humboldt's Foundation in Goettingen, Germany between 1943-1944, he found new absorption bands pertaining to small-size F center aggregates and followed their interconversions. A primary photochemical solid state reaction was evidenced for the first time leading to nanoscale products.