A general purpose cold finger using a vibration-free mounted He closed-cycle cryostata)

A method for mounting a He closed-cycle cryostat which consists of an exchange gas envelope around the cold head to cool an independently supported sample mount as in model DE202 with a DMX-20 interface from APD Cryogenics, Inc. is described. No detectable vibration of the sample mount is observed as evaluated using 57Fe Mossbauer spectroscopy and a piezoelectric accelerometer. Using a 25 ,um thick a+Fe foil a linewidth of 0.231(3) mm/s at 300 K with the refrigerator on and the same linewidth with the refrigerator off is observed. The easy optical access afforded by such a cold finger makes it an economical general purpose laboratory tool for performing low-T spectroscopic investigations, such as microwave, optical, yray, x-ray and neutron-scattering measurements. Other applications include electrical transport, SIMS, RBS, and rare-gas matrix isolation. Q 1995 American Ins&z&e of Physics.