There are some methods to observe Raman bands of fluorescent materials:

1) using exciting laser lines with long wavelengths (in the spectral region of the red or infrared radiation) one can prevent electronic absorption and thus fluorescence; however, the intensity of Raman scattering results lower than that obtained with excitation laser lines with shorter wavelengths (for example, in the blue or green light region);

2) in the region of anti-Stokes scattering, fluorescence does not occur and therefore it is possible to observe Raman bands (especially those with minor Raman shifts), although of much lower intensities than those of the corresponding Raman bands in the region of Stokes scattering;

3) by strong interaction with Ag or Au nanoparticles it is possible to observe Raman bands by means of the SERS (surface-enhanced Raman scattering) effect, with marked fluorescence quenching.

However, failing to provide different exciting laser lines nor appropriate SERS substrates, it is possible to mitigate the fluorescence emission, favoring non-radiative decay from the excited electronic state of the sample molecules, for heat exchange with surrounding molecules, for example by finely mixing fluorescent solid samples with KBr powder.

In agreement with the previous note:

- you should try to change the laser wavelength (red, green, blue)

- you should check out the solvent (it may be fluorescent by itself or it may contain some impurity which does)

If you compound to be studied is fluorescent by itself at all wavelengths available, you should use another technique (dependng on your problem to be solved, eg. IR)

Dear Grabiela, I agree with all the answers, you could try changing the wavelength of your laser to 785, which energy is not enough to give fluorescent. In other hand, metal nanoparticles such as gold and silver, provoke the quenching of fluorescence, and in addition, you can get the Surface Enhanced Raman Scattering (SERS) of your samples.

DearGrabiela, if you are working at low concentrations, i think you have very difficult time to get a spectrum of your sample at 785 nm or 1064 nm (where you can normally avoid fluorescence). i would recommend you to try deep UV laser (244 nm or 266 nm), where you get the benefit from resonance enhancement and as carlos caro mentioned SERS is another option, cheers

Thank you all for your thoughtful responses!!

In order to produce fluorescence, the molecules must absorb at the source wavelength and then emit. I do not believe that any of your constituent components do this at 514nm. Thus, what appears to be fluorescence can be Rayleigh scattering of your source and even the Raman of your sample, which enters the spectrometer as stray light, and is registered across the detector, therefore resembling broad band fluorescence. We have studied this in protein powders and tissue samples.

"In vitro analysis of immersed human tissues by Raman microspectroscopy",

F. Bonnier, A.Mehmood, P. Knief, A. Meade, W. Hornebeck, H. Lambkin, K. Flynn, V. McDonagh, C. Healy,T.C. Lee, F.M. Lyng, H.J. Byrne,

Journal of Raman Spectroscopy, 42, 888–896(2011)

I would suggest sonicating your sample, or filtering to remove any aggregates. The use of a confocal hole can also reduce the scattering from solid samples.

Try to obtain the derivative of your spectrum: spectral bands are usually sharper (higher derivatives) then the broad fluorescence backgrounds 

If there are some fluorescent impurities, which can present this phenomenon, you  can to adsob them on the activ charcoal. After that you must obtrain the absoption spectra to to locate the absorption band and the avoid this spectral range with Raman excitation line. SERS spectra is another posibility, but ,be carefull because SERS spectrum have some diferences by compoaring with normal Raman spectrum.

There are some methods to observe Raman bands of fluorescent materials:

1) using exciting laser lines with long wavelengths (in the spectral region of the red or infrared radiation) one can prevent electronic absorption and thus fluorescence; however, the intensity of Raman scattering results lower than that obtained with excitation laser lines with shorter wavelengths (for example, in the blue or green light region);

2) in the region of anti-Stokes scattering, fluorescence does not occur and therefore it is possible to observe Raman bands (especially those with minor Raman shifts), although of much lower intensities than those of the corresponding Raman bands in the region of Stokes scattering;

3) by strong interaction with Ag or Au nanoparticles it is possible to observe Raman bands by means of the SERS (surface-enhanced Raman scattering) effect, with marked fluorescence quenching.

However, failing to provide different exciting laser lines nor appropriate SERS substrates, it is possible to mitigate the fluorescence emission, favoring non-radiative decay from the excited electronic state of the sample molecules, for heat exchange with surrounding molecules, for example by finely mixing fluorescent solid samples with KBr powder.

Try to record the first or second derivative of the graph

Try a confocal set up by closing down the slit width to maybe 20um

Amino acids do not absorb at 514nm, and therefore do not fluoresce. What you are observing is scattering of the laser and Raman bands themselves, which enters the spectrometer as stray light.

"In vitro analysis of immersed human tissues by Raman microspectroscopy",

F. Bonnier, A.Mehmood, P. Knief, A. Meade, W. Hornebeck, H. Lambkin, K. Flynn, V. McDonagh, C. Healy,T.C. Lee, F.M. Lyng, H.J. Byrne,

Journal of Raman Spectroscopy, 42, 888–896(2011)

This is most likely coming from your buffer or small aggregates of solute. Moving to 785nm will not help in this case - it will reduce the scatter but also the Raman as they are both wavelength dependent. Try changing the buffer, or sonicating to breakdown any aggregates.  Alternatively, use a more concentrated solution, so that you can the the Raman spectrum, and start working down in concentration.