Question

Why the sample is placed at 90 degree in fluorescence spectra?

Answer 1

because emission spectrum the intensity is dependent on the:

=Excitation wavelength
=Concentration of the analyte solvent
=Path length of the cuvette
=Self-absorption of the sample

hope it helps

Answer 2

The light that exits comes out at a specific angle depending on its wavelength. The sample emits a wavelength, which travels to the detector. The detector is usually set at a 90-degree angle to the light source to avoid any interference from the transmitted excitation light.

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