The Frequency Doubled, Synchronously Pumped Dye Laser as a Source for Resonance Raman Spectroscopy of Nucleic Acid Constituents

Abstract

The use of ultraviolet radiation for obtaining Raman spectra of nucleic acids, their constituents, and polynucleotides allows, through resonance and preresonance enhancement, both the reduction of detectable solution concentrations by several orders of magnitude and the determination of the electronic source of Raman intensities. Low repetition rate (<100 Hz) pulsed lasers, used in previous experiments to achieve adequate uv power, prevented incorporation of high sensitivity photon counting detection electronics. In this note it is demonstrated that the high repetition rate, frequency doubled, synchronously pumped dye laser (SPDL), while compatible with photon counting electronics, provides sufficient uv powers for obtaining satisfactory Raman spectra at low concentrations. This system possesses the added advantage that it is built from lasers widely used for conventional visible Raman spectroscopy. In addition, the optical pulse width is narrow enough (<10 ps) to allow the potential for time resolved rejection of fluorescence.