Rapid shifted excitation Raman difference spectroscopy with a distributed feedback diode laser emitting at 785 nm |
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| Authors: | M Maiwald G Erbert A Klehr H-D Kronfeldt H Schmidt B Sumpf G Tränkle |
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| Institution: | 1. Ferdinand-Braun-Institut für H?chstfrequenztechnik, Gustav-Kirchhoff-Strasse 4, 12489, Berlin, Germany
2. Optisches Institut, Technische Universit?t Berlin, Hardenbergstr. 36, 10623, Berlin, Germany
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| Abstract: | A distributed feedback (DFB) laser diode emitting at 785 nm was tested and applied as a light source for shifted excitation Raman difference spectroscopy (SERDS). Due to the physical properties of the laser diode, it was possible to shift the emission wavelength by 8 cm-1 (0.5 nm) required for our SERDS measurements by simply changing the injection current. The internal grating ensured single mode operation at both wavelength with the frequency stability of ±0.06 cm-1 (0.004 nm) required for high resolution Raman spectroscopic applications. The shifted spectra were used for calculating enhanced Raman spectra being obscured by a strong scattering background. A 16 dB (≈38 fold) improvement of the signal-to-background noise S̄/σB was demonstrated using blackboard chalk as a sample. The tunable DFB laser is a versatile excitation source for SERDS, which could be used in any dispersive Raman system to subtract fluorescence contributions and scattering background. PACS 82.80.Gk; 42.55.-f; 42.64.Fi |
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