Question

Often students confuse the instrumentation of a fluorimeter with the instrumentation of a Raman spectrometer. Discuss the similarities and differences between the two and explain how fluorescence is often troublesome for Raman spectroscopists.

Answer 1

Step 1

Similarity of fluorimeter and raman spectrometer.

Fluorimeter	Raman spectrometer
In fluorimeter, electron of sample get excited by using UV.	UV is also used to excite the electrons to higher state for detection of peaks.
Filter is required for filtering the scattered light of flouroscence.	Filter is required for the deposition of scattered light.
Grating for the diffraction of scattered light is required.	Grating is also required for diffraction for the bending of light.
Detector is required for detecting the light.	Detector is also required for detecting the transmitted light.

Step 2

Disimilarity of fluorimeter and raman spectrometer.

Fluorimeter	Raman spectrometer
It depends on intensity of luminescence.	It depends on intensity of excitation of light.
Wavelength of light is 190 to 1100 nm.	Wavelength is 224 to 248 nm.
Filter only filters the scattered light.	Filter filters the anti stokes light.
Polarizablity of the solution remain the same throughout the detection.	Polarizablity of the solution get changes for the good appearance of signal.

Step 3

In fluorescence, excitation of electrons taking place for which UV is required and appearance of fluorescence takes place in solution specifically with very concentration even after clearing the cuvette with water or HNO3 solution. This appearance of fluorescence is known as fluorescence masking and results in disappearance of peaks of raman.

However, trouble in fluorescence arises either due to impurities or relaxation of process. This overall relaxation results from absorption of electrons in resonance of raman spectroscopy.

The only way is the signals of raman can be calibrated on mode of higher frequency with fluorescence.