Shifted Excitation Raman Difference Spectroscopy - From Diode Lasers to in-situ Applications

Shifted excitation Raman difference spectroscopy (SERDS) will be presented using customized diode lasers for the excitation. Here, hybrid diode laser based light sources at 671 nm and 488 nm and monolithic devices at 671 nm and 785 nm are shown as an example. Electro-optical and spectral properties are discussed with respect to the application. Raman experiments demonstrate their suitability as an excitation source for SERDS. The hybrid and monolithic concepts are transferable to other wavelengths. A portable SERDS sensor system including an in-house developed handheld probe is realized for in-situ investigations and will be described. Outdoor SERDS experiments in the apple orchard are performed and demonstrate SERDS as a powerful and easy-to-use tool which improves Raman spectroscopic experiments especially for in-situ investigations.