Synthesis, structure, thermal and non-linear optical properties of L-argininium hydrogen selenite

L-Argininium hydrogen selenite (C(6)H(15)N(4)O(2)HSeO(3)) is a new semiorganic compound of the hydrogen selenite family with non-linear optical properties. The crystal lattice is monoclinic with unit-cell parameters a = 22.493 (5), b = 5.1624 (13), c = 9.730 (4) A, beta = 95.68 (3) degrees, V = 1124.3 (6) A(3), Z = 4, space group C2. Second-harmonic generation measurements performed on powder samples, using a Q-switched Nd:Yag laser (lambda = 1064 nm), showed the second-harmonic power to be about twice that of urea. Differential scanning calorimetry measurements revealed the existence of a phase transition with onset at 289 K.