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Updated: Mar 17, 2026

Rejection of Fluorescence Background in Resonance and Spontaneous Raman Microspectroscopy
Published on: May 18, 2011
Communication: The origin of many-particle signals in nonlinear optical spectroscopy of non-interacting particles
1Department of Chemistry and Department of Physics and Astronomy, University of California, Irvine, California 92697, USA.
Abstract:
Nonlinear spectroscopy signals detected by fluorescence from dilute samples of N non-interacting molecules are usually adequately described by simply multiplying the single molecule response by N. We show that signals that scale with higher powers of N are generated by the joint detection of several particles. This can be accomplished by phase sensitive detection such as phase cycling, photo-acoustic modulation, or by Hanbury-Brown Twiss photon coincidence. Such measurements can dissect the ensemble according to the number of excited particles.
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