Chromatic polarization in solid parahydrogen with an argon impurity at an extremely low concentration

The effect of chromatic polarization observed in samples prepared for studying thermal conductivity of weak solid solutions (p-H₂)_{1 − x} Ar _x has been described. Bulk cylindrical samples have been grown in a molybdenum glass ampule through desublimation followed by control of their quality in polarized light. In contrast to weak solid solutions (p-H₂)_{1 − x} Ne _x with a heavy quasi-isotopic neon impurity, the samples with argon at the same concentrations (several parts per million) exhibit inclined chromatic bands due to elastic mechanical stresses induced after cooling to liquid-helium temperature.