Journal of Electrostatics, 21 (1988) 145-149 145 Elsevier Science Publishers B.V., Amsterdam -- Printed in The Netherlands A NOVEL SAMPLE-PREPARATION TECHNIQUE FOR INFRARED AND FAR-INFRARED SPECTROSCOPY F. KREMER Max-Planck-Institut fgtr Polymerforschung, Postfach 3148, 6500 Mainz (F.R.G.) A. MASON University of Bath, School of Physics, Bath BAZ 7A9 (Great Britain) and D. B(~HME Max-Planck-Institut fiir Festk6rperforschung, Heisenbergstrasse 1, 7000 Stuttgart 80 (F.R.G.) (Received January 18, 1988; accepted April 14, 1988) Summary A novel technique of preparing thin ( < 10 #m) homogeneous samples for infrared (IR) and far- infrared (FIR) spectroscopic studies is presented. In contrast to conventional methods (e.g. cast- ing a film from solution, pressing a pellet of a mixture of KBr with the sample), the material to be studied is dissolved in a suitable solvent and made into an aerosol by use of an ultrasonic vaporizer. The sample material is then freeze dried on a substrate mounted on a temperature- controlled (100 K to 300 K) cold finger of a cryostat placed in a glass chamber. By this method, especially highly crystalline materials obtained in powder form can easily be prepared as thin solid films with a diameter of about 20 mm. Introduction Infrared (IR) but especially far-infrared (FIR) spectroscopy requires sam- ples that are homogeneous in thickness over a diameter of about 20 mm be- cause otherwise scattering may spoil the measurements. This causes serious problems for crystalline materials which are often obtained in a powder form (e.g. biological samples like lysozyme, alcohol dehydrogenase (ADH), sugars ). For these materials [1,2] the usual preparation method of casting a film from solution on a suitable window-substrate is hardly applicable because crystal- lization results in the formation of small crystals of a few millimeters in di- ameter. An alternative approach would be to prepare a mixture of the material under study with an inert matrix such as KBr. By pressing a pellet from this mixture a disc-shaped sample is obtained. The major disadvantage with this method is that the influence of matrix material on vibrational modes of the sample molecules cannot easily be calculated, especially at FIR-frequencies. It 0304-3886/88/$03.50 © 1988 Elsevier Science Publishers B.V.