Variable Temperature Diffraction

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We propose to purchase a variable temperature cryostat for our single crystal X-ray diffractometer. This is a critical piece of infrastructure which is required for the NSERC supported innovative research in the applicant's labs. Temperature has a significant effect on the diffraction of x-rays with lower temperatures leading to significantly enhanced(stronger) reflection intensities, and often better defined thermal parameters. For fluorinated and halogenated compounds these temperature effects become significant and can lead to a temperature dependent loss of high angle peaks and thus resolution of the final structure. This can make a difference in the acceptability of a structure result during review and thus final publication. Significantly though, the use low temperature is now routine in many facilities due to systematic improvements in the data collected and the final models. In addition to these factors, many compounds undergo temperature dependent phase transitions and control of the temperature is critical for the determination of these phases. The instrument to be purchased is an Oxford 1000 low temperature cryostat which replace a failed and irreparable Bruker Cryostream unit fitted onto an ApexII Bruker diffractometer. This twenty year old unit has been repaired twice(by Bruker) and deemed irreparable after the last technicians visit in 2019. This infrastructure will not only support the three CoPI's of this application but be used to train an average of 17 HQP annually. It will be open to other users and it will support much our current research and the continued frontline research described in this proposal.