Alexander Edgar Douglas

Alexander "Alex" Edgar Douglas, FRSC FRS (12 April 1916, in Melfort, Saskatchewan 26 July 1981, in Ottawa) was a Canadian physicist, known for his work in molecular spectroscopy. He was president of the Canadian Association of Physicists in 1975–1976.[1]


Born on a farm in Saskatchewan, Douglas received his BA and MA degrees from the University of Saskatchewan. Gerhard Herzberg was his MA thesis advisor. During World War II, Douglas interrupted his studies to do military-related research in the Physics Division at the NRC. After the war, he earned his PhD in physics at Pennsylvania State University under David H. Rank. In 1949 Douglas became NRC's head of the Spectroscopy Section of the Physics Division, which was directed by Gerhard Herzberg. From 1969 to 1973 Douglas was the director of the Physics Division of the NRC. He returned to his previous job as head of the Spectroscopy Section in 1973 and remained in that position until his retirement from the NRC in 1980.

A. E. Douglas was the first to observe the spectra of B2, Si2, CH+, SiH+, NF, PF, BN, CN+ and many other diatomic or triatomic molecules. He first identified the 4050 group of lines observed in comets as being due to the C3 molecule. Using a method that he developed, Douglas made the first studies of the Zeeman effect in polyatomic molecules.[2]

According to Gerhard Herzberg:[2]

One of Douglas' most important contributions was his recognition of the reason for "anomalous lifetimes," that is, the failure of a simple relationship between absorption coefficient and lifetime to account for lifetimes in such compounds as NO2, SO2, C6H6. This phenomenon, referred to in the most recent literature as the Douglas effect, is closely connected with internal conversion in larger molecules.

In astrophysical applications of molecular spectroscopy, Douglas is known for his identification of interstellar CH+ and of cometary C3 and for the reproduction in the laboratory of the Meinel bands of N2+ and other spectra.[2][3][4]

Honours and awards


  1. "Alexander Edgar Douglas". The Canadian Encyclopedia.
  2. 1 2 3 Herzberg, G. (Oct 1981). "Obituary: Alexander E. Douglas". Physics Today. 34 (10): 116–177. Bibcode:1981PhT....34j.116H. doi:10.1063/1.2914316.
  3. Dalby, F.W.; Douglas, A.E. (Nov 1951). "Laboratory Observation of the A2∏ — X2Σ Bands of the N2+ Molecule". Phys Rev. 84 (4): 843–843. Bibcode:1951PhRv...84Q.843D. doi:10.1103/PhysRev.84.843.
  4. Douglas, A. E. (1953). "Analysis of the 2∏-2Σ Bands of the N2+ Molecule". Astrophysical Journal. 117: 380–386. Bibcode:1953ApJ...117..380D. doi:10.1086/145703.

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