Ultraviolet micro-Raman spectrograph for the detection of small numbers of bacterial cells
Date of Original Version
The construction of a practical UV micro-Raman spectrograph capable of selective excitation of bacterial cells and other microscopic samples has been described. A reflective objective is used to focus cw laser light on a sample and at the same time collect the scattered light at 180°. With the aid of a quartz lens the image produced is focused on the slits of a spectrograph equipped with a single 2400 grooves/mm grating optimized for 250 nm. Spectra were detected by means of a blue-intensified diode array detector. Resonance Raman spectra of Bacillus subtilis and Flavobacterium capsulatum excited by the 257.2 nm output of a cw laser were recorded in the 900-1800 cm-1 region. Bacterial cells were immobilized on a quartz plate by means of polylysine and were counted visually. Cooling was required to retard sample degradation. Sample sizes ranged from 1 to 50 cells with excitation times varying from 15 to 180 s. Excellent spectra have been obtained from 20 cells in 15 s using a spectrograph having only 3% throughput.
Publication Title, e.g., Journal
Review of Scientific Instruments
Chadha, S., W. H. Nelson, and J. F. Sperry. "Ultraviolet micro-Raman spectrograph for the detection of small numbers of bacterial cells." Review of Scientific Instruments 64, 11 (1993). doi: 10.1063/1.1144313.