Abstract: A system for attenuating the inherent vibration associated with a mechanical refrigeration unit employed to cryogenically cool sensitive instruments used in measuring chemical constituents of the atmosphere. A modular system including an instrument housing 13 and a reaction bracket 14 with a refrigerator unit 15 "floated" therebetween comprise the instrumentation system. A pair of evacuated bellows 20,25 "float" refrigerator unit 15 and provide pressure compensation therefor at all levels of pressure from sea level to the vacuum of space. Vibration isolators 27 (FIG. 1) and 57 (FIG. 2) when needed provide additional vibration damping for refrigerator unit 15. Flexible thermal strap 38 (20.degree. K.) serves to provide essentially vibration free thermal contact between cold tip 32 of refrigerator unit 15 and the instrument component 37 mounted on TDL mount 36. Another flexible strap 41 (77.degree. K.