Development of Microminiature Joule-Thomson Refrigerators and Their Application to the Infrared Spectroscopy of One - Conductors.

The development of microminiature Joule-Thomson refrigerators is described. These refrigerators are fabricated from glass slides using a novel photolithographic method, and have been operated to 80K using nitrogen as the refrigerant. Their performance is consistent with relations describing fluid friction and heat transfer in large channels, with allowance made for surface roughness. Approaches to multistage refrigerators to reach 20K and 4K are discussed. Microminiature refrigerators were used as sample mounts to study changes with temperature in the infrared absorption spectra of three complexes of TCNQ, as they each undergo a metal-insulator transition. The results demonstrate the existence of electron -intramolecular vibration coupling in these one-dimensional materials. Some differences from other TCNQ complexes are attributable to the lowered symmetry of the TCNQ molecule in the stacks. The blue-shift of an absorption peak in the CN triple-bond stretching region is observed, suggesting the involvement of CN groups in interchain coupling.