In most cases, UV (ultra violet) light is sufficient to break molecular bonds. Electrons from calcium or magnesium atoms can be removed by X-rays up to and above the k-shell binding energy (=202 x 13.6 eV for calcium, and 122 x 13.6 eV for magnesium). I do not know of any resonant frequency to shatter the molecules, although in certain cases, IR (infra red) light can break molecular bonds.