Editing Raman spectroscopy (section)

== History ==
Although the inelastic scattering of light was predicted by [[Adolf Smekal]] in 1923,<ref>{{cite journal |last1=Smekal |first1=A. |year=1923 |title=Zur Quantentheorie der Dispersion |journal=Die Naturwissenschaften |volume=11 |issue=43 |pages=873–875 |bibcode=1923NW.....11..873S |doi=10.1007/BF01576902 |s2cid=20086350}}</ref> it was not observed in practice until 1928. The Raman effect was named after one of its discoverers, the Indian scientist [[C. V. Raman]], who observed the effect in organic liquids in 1928 together with [[K. S. Krishnan]], and independently by [[Grigory Landsberg]] and [[Leonid Isaakovich Mandelstam|Leonid Mandelstam]] in inorganic crystals.<ref name="Gardiner" /> Raman won the [[Nobel Prize in Physics]] in 1930 for this discovery. The first observation of Raman spectra in gases was in 1929 by [[Franco Rasetti#Raman spectroscopy and the model of the atomic nucleus|Franco Rasetti]].<ref>[http://oralhistories.library.caltech.edu/archive/00000070/01/OH_Rasetti.pdf Caltech oral history interview] by [[Judith R. Goodstein]], 4 February 1982</ref><ref>{{cite journal|author=Battimelli, Giovanni|title=Obituary: Franco Rasetti|journal=Physics Today|date=December 2002|volume=55|issue=12|pages=76–78|doi=10.1063/1.1537927|bibcode = 2002PhT....55l..76B |doi-access=free}}</ref>

Systematic pioneering theory of the Raman effect was developed by Czechoslovak physicist [[George Placzek]] between 1930 and 1934.<ref>{{Cite book |last=Placzek |first=G |title=Handbuch der Radiologie |publisher=[[Akademische Verlagsgesellschaft]] |year=1934 |volume=6,2 |location=Leipzig |pages=209 |language=de |chapter=Rayleigh-Streuung und Raman-Effekt}}</ref> The mercury [[arc lamp|arc]] became the principal light source, first with photographic detection and then with spectrophotometric detection.

In the years following its discovery, Raman spectroscopy was used to provide the first catalog of molecular vibrational frequencies. Typically, the sample was held in a long tube and illuminated along its length with a beam of filtered [[monochromatic]] light generated by a [[gas discharge lamp]]. The photons that were scattered by the sample were collected through an [[optical flat]] at the end of the tube. To maximize the sensitivity, the sample was highly concentrated (1 M or more) and relatively large volumes (5 mL or more) were used.