Anomalous absorption of Cr3+ electron spin resonance line intensities in guanidinium aluminum sulfate hexahydrate crystals

Experimental results are presented describing an anomalous absorption observed as a function of temperature for Cr3+ impurity ions in guanidinium aluminum sulfate hexahydrate (GAlSH) crystals. Measurements were made of the Cr3+ electron spin resonance line intensities, and a plot of the results upon cooling and warming the crystal shows the presence of an anomaly centered at a temperature of 280 K. The same effect was observed in measurements of the capacitance of undoped GAlSH crystals. The anomaly was found to be enhanced by the application of radio frequency power at 200 MHz to the crystal.