Conventional flow cytometry uses mirrors and filters to select specific wavelength ranges for detection of signal from different fluorophores on individual PMTs. Spectral flow cytometry uses dispersive optics, such as prisms or gratings, to disperse the collected light across a detector array, allowing the full spectra from each particle to be measured. Spectral unmixing or other analyses can then be performed on the spectral data to determine the amount of individual fluorophore contributing to the mixture spectra or extract other information from the spectra. Spectral flow cytometry represents a new approach to instrument design, and enables new classes of applications not possible with conventional flow cytometry.

Selected References:

High throughput single nanoparticle spectroscopy.
David S Sebba, Dakota A Watson and John P Nolan (2009).
ACS Nano 2009; 3:1477-1484.

Spectral measurements of large particles by flow cytometry.
Watson DA, Gaskill DF, Brown LO, Doorn Sk, Nolan JP (2009).
Cytometry 75:460-4.

Single cell analysis using surface enhanced Raman scattering (SERS) tags.
Nolan, J.P., E. Duggan, E Liu, D. Condello, I. Dave, S.A. Stoner (2012). 
Methods 57:272-9.

Visible and near infrared fluorescence spectral flow cytometry.
Nolan, J.P., D. Condello, E. Duggan, M. Naivar, D. Novo (2013).
Cytometry 83A: 253-264.

Spectral flow cytometry.
Nolan, J.P. and D. Condello (2013).
Current Protocols in Cytometry 1.27.1-1.27.13.

Surface Enhanced Raman Scattering (SERS) Image Cytometry for High Content Screening.
Liu, E., J.P. Nolan (2014).
Advanced Flourescence Microscopy Techniques (PM Conn, ed),Elsevier.

Optimization of SERS tag intensity, binding footprint, and emittance.
Nolan, J.P., E. Duggan, D Condello (2014).
Journal of Bioconjugate Chemistry 25: 1233–1242.