Klarite substrates are fully compatible with most Raman spectrometers and are available mounted on standard 75mm microscope slides for ease of handling and compatibility with microscope equipped Raman systems.
An increasing range of miniature and portable Raman spectrometers are also available and high quality spectra can be obtained from Klarite. Optical fibre based sample probes can also be used to record spectra including both single fibre and fibre bundle based systems.
When using a miniature or portable Raman system it is necessary to have a mechanical mount to hold the substrate and adjust its position at the laser focus of the system. Mesophotonics are developing a range of substrate interfaces - please contact us for more information.
The spot size and laser power incident on the substrate can vary significantly between different Raman systems. Tests have shown high quality data is obtained with a large range of spot sizes from 7mm to <5um in diameter. Very small spot sizes less than 5um that result from using >50x focusing objectives with microscopes systems should be avoided as they reduce enhancement.
Laser powers from <100uW to >300mW have been shown to produce excellent Raman spectra with Klarite. Powers at the higher end of this range are required for larger spot sizes and fibre coupled systems. Higher powers are unlikely to damage the Klarite surface, but care should be taken to damaging the deposited sample. Due to the high enhancement of the Klarite surface significantly lower powers and lower integration times are normally required relative to those used in regular none enhanced Raman.
Surface enhanced Raman is a wavelength dependent phenomena and current Klarite substrates are designed to work with red and near infrared excitation lasers (633-800nm). Use at shorter wavelengths, e.g. 532nm is possible, however gold absorbtion at this wavelength can cause thermal signatures to dominate data unless very low powers of <1mW are used. For longer wavelengths, e.g 1um, standard Klarite will only give a small signal enhancement. For optimum operation Mesophotonics recommends using Raman systems with either 785nm or 633nm excitation. If you are interested in excitation at other wavelengths please contact us as we have future products in development to expand this operating range.