| The millimeter/submillimeter portion of the electromagnetic spectrum is able to address fundamental questions in astronomy, cosmology, atmospheric science, molecular physics, quantum electronics, plasma physics, and other fields. Also, this spectral region has transmission characteristics which make it desirable for communications within the atmosphere and potentially for imaging.; In order to demonstrate that detector technology in this region is sufficiently mature to permit the construction of reliable quasi-optical devices using off the shelf components, we have generated passive images using a broadband detector cooled to 0.35 K with a commercially produced {dollar}sp3{dollar}He refrigerator. We have shown the possibility of an extremely simple, highly sensitive, passive imaging system which operates in an attractive spectral region and is capable of upscaling to provide practical spatial resolution and real time operation over useful ranges.; International public concern about acid rain, ozone depletion, and urban smog has spurred intense study of atmospheric chemistry. Spectra of two minor atmospheric constituents (HNO{dollar}sb3{dollar}, {dollar}sp{lcub}16{rcub}{dollar}O{dollar}sp{lcub}18{rcub}{dollar}O) have been studied in the laboratory to assist with remote monitoring of atmospheric dynamics, modelling of atmospheric chemistry, and selection of communication frequencies which have some immunity to atmospheric perturbations. The nitric acid observations have allowed us to determine effective rotational constants for the first five vibrational states ({dollar}nusb0{dollar}, {dollar}nusb9{dollar}, {dollar}nusb7{dollar}, {dollar}nusb6{dollar}, {dollar}nusb8{dollar}) and assign transitions in the perturbed {dollar}nusb5{dollar} state. In addition, the concentration of {dollar}sp{lcub}16{rcub}{dollar}O{dollar}sp{lcub}18{rcub}{dollar}O in interstellar molecular clouds has been identified as a key discriminator between competing models of stellar formation; the measurements presented here will assist astronomers attempting to determine the abundance of this species in molecular clouds and proto-stars.; We have recorded and analyzed the spectra of two important lasing species ({dollar}sp{lcub}12{rcub}{dollar}CH{dollar}sb3{dollar}F, {dollar}sp{lcub}12{rcub}{dollar}CH{dollar}sb2{dollar}F{dollar}sb2{dollar}). We have also determined the collisional broadening parameters for a number of transitions in n3 excited vibrational state of {dollar}sp{lcub}12{rcub}{dollar}CH{dollar}sb3{dollar}F.; Since the absolute frequency stability and reproducibility of OPFIR lasers is of considerable interest, we have studied the gain profile of {dollar}sp{lcub}12{rcub}{dollar}CH{dollar}sb3{dollar}F as a function of both pump offset and pressure; this is in response to a current controversy concerning possible large pressure shifts which may occur in some OPFIR lasers. We have been able to place a stringent upper limit on the presence of such shifts in longitudinally pumped lasers. (Abstract shortened with permission of author.)... |
