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McCall, Benjamin J. McCall, Benjamin J. Gruebele, Martin Hirata, So Scheeline, Alexander Porambo, Michael W 2015-09-29T20:38:08Z 2015-09-29T20:38:08Z 2015-08 2015-07-08 The study of molecular ions is relevant to many areas of scientific interest. Mid-infrared laser spectroscopy functions as a useful tool for understanding the role of molecular ions in these areas. To this end, a broadly tunable mid-infrared difference frequency generation noise-immune cavity-enhanced optical heterodyne molecular spectroscopy (NICE-OHMS) system has been developed and characterized through rovibrational spectroscopy of methane. In addition, an attempt was made to use this spectrometer to probe molecular ions focused into an ion beam. Challenges inherent to laboratory molecular ion spectroscopy, such as quantum dilution at high internal temperatures and low ion number density, have been addressed through the development of an instrument that produces rotationally cooled molecular ions coupled to the highly sensitive spectroscopic technique NICE-OHMS. The instrument was first explored as an extension of an ion beam spectrometer by the integration of a continuous supersonic expansion discharge source for the production of the cooled molecular ions. Issues with the implementation led to the re- design of the instrument for spectroscopically probing a supersonic expansion discharge directly with NICE-OHMS. After implementing discharge modulation of the supersonic expansion source, spectra of rotationally cooled H3+ and HN2+ were acquired. This instrumental development and preliminary spectroscopy has paved the way for a new method for the sensitive spectroscopic study of cooled molecular ions that will aid further insight into these chemical species in many fields. Submission original under an indefinite embargo labeled 'Open Access'. The submission was exported from vireo on 2015-09-29 without embargo terms 2015-8 The student, Michael Porambo, accepted the attached license on 2015-07-07 at 15:53. The student, Michael Porambo, submitted this Dissertation for approval on 2015-07-07 at 16:09. This Dissertation was approved for publication on 2015-07-08 at 11:18. DSpace SAF Submission Ingestion Package generated from Vireo submission #8362 on 2015-09-29 at 13:22:10 Made available in DSpace on 2015-09-29T20:38:08Z (GMT). No. of bitstreams: 2 PORAMBO-DISSERTATION-2015.pdf: 12201326 bytes, checksum: 9f5191e9ec727c29b44de6e51e483316 (MD5) LICENSE.txt: 4212 bytes, checksum: a22c55c801adaf5753f4b9cdfa342dc2 (MD5) Previous issue date: 2015-07-08 application/pdf http://hdl.handle.net/2142/88006 en Copyright 2015 Michael W. Porambo spectroscopy molecular ion infrared supersonic expansion ion beam cavity-enhanced technique Development of a sensitive mid-infrared spectrometer for the study of cooled molecular ions text text Chemistry Chemistry University of Illinois at Urbana-Champaign Dissertation Ph.D.