Effect of mechanical stress on the line width of single photon absorptions in Mn12-acetate

Quantum mechanical tunneling of the magnetic moment has been observed in several single-molecule magnets, including Mn-12-acetate, but the tunneling mechanism is not entirely understood. It has been proposed that tunneling occurs due to defects in the crystal structure. These defects can be studied through their effect on the inhomogeneous line width of single photon (intrawell) transitions. However, most previous studies of the line width have been performed on crystals that have been pressed into pellets, which may introduce additional defects into the crystal structure. We report on measurements of the line width of loose crystals using the method of time-domain terahertz spectroscopy. The line width is not significantly reduced from the measurements on pressed pellets. (C) 2003 Elsevier Science B.V. All rights reserved.