In 1941, he returned to Quebec and became a lecturer at Université Laval.[2] He was appointed a professor in 1947 and was head of the Department of Chemistry from 1957 to 1968.[1]
His research was in infrared and Raman spectroscopy and the determination of molecular and crystal structure.[1] In 1946 and 1948, he was awarded a Guggenheim Fellowship in chemistry for the investigation of the molecular structure of hydrogen peroxide by infrared spectroscopy, which showed that this molecule has a skewed or nonplanar structure.[2][3][4] In 1956 with Michael Falk, he obtained the infrared spectrum of the hydronium ion, previously believed to be too short-lived to observe a spectrum.[2][5] In 1958-1959 he investigated the anomalous thermodynamic properties of ice.[6] In 1970-75, his group observed the first infrared and Raman vibrational spectra of hydrogen trioxide (H2O3) in dilute aqueous solution.[7] In 1976 with Sylvia Turrell, he showed that the weak acidity of hydrogen fluoride is due to the formation of a tightly bound ion pair [H3O+·F−].[2][8]
In 1970, he was made a Companion of the Order of Canada for "his research work in physical chemistry".[10] In 1970, he was awarded an honorary Doctor of Science degree from the Université de Sherbrooke.[1]
^Falk, Michael; Giguère, Paul A. (October 1957). "Infrared spectrum of the H3O+ ion in aqueous solutions". Canadian Journal of Chemistry. 35 (10): 1195–1204. doi:10.1139/v57-160.
^Journal of Physics and Chemistry of Solids, oct 1959
^Giguère, Paul A.; Turrell, Sylvia (1980). "The nature of hydrofluoric acid. A spectroscopic study of the proton-transfer complex H3O+...F−". J. Am. Chem. Soc.102 (17): 5473. doi:10.1021/ja00537a008.