Temperature dependence of the chlorine 35 quadrupole interaction in ammonium perchlorate from 4K to 340K

Abstract A nuclear magnetic resonance study of the 35 Cl quadrupolar interaction in single crystal and polycrystalline ammonium perchlorate (APC) at 2T and 7T yields a value of = 320(20)kHz and =0.80(10) at 300 K. The temperature dependence is approximately -0.1 kHz /kat 340K, zero at 300 K, +3 kHz/K near 40 K and the quadrupole coupling passes smoothly through zero near 20 K. At 4.2K is approximately 50kHz, presumably of opposite sign to that at 300K, and with a finite temperature dependence. Anomalies near 200 K and 20 K are observed in the satellite behavior. The former is a doubling of the satellite line with a □H and increased separation with b □H, which exhibit time dependence. The 20 K anomaly is a frequency arrest for a range of about 5 K.