On-Chip Lock-In Detection for Ultrafast Spectroscopy of Single Particles

• DOI: 10.1021/acs.jpcc.4c01814
• Publication Date: 2024-05-16T12:54:25Z
• Authors: Subhasis Adhikari; Niklas Gross; Kelly S. Wilson; Ojasvi Verma; Zhenyang Jia; Christy F. Landes; Sean T. Roberts; Stephan Link
• Keywords: Lock (firearm)

Time-resolved spectroscopy of plasmonic nanoparticles is a vital technique for probing their ultrafast electron dynamics and subsequent acoustic photothermal properties. Traditionally, these experiments are performed with spectrally broad probe beams on the ensemble level to achieve high signal amplitudes. However, relaxation highly dependent size, shape, crystallinity. As such, inherent heterogeneity most nanoparticle samples can complicate efforts build microscopic models solely basis measurements. Although approaches collecting time-resolved microscopy signals from individual at selected wavelengths have been demonstrated, acquiring spectra single objects remains challenging. Here, we demonstrate an alternate method that efficiently yields gold nanodisk in one measurement. By modulating frequency-doubled output 96 MHz Ti:sapphire oscillator 8 kHz, able use lock-in pixel-array camera detect photoinduced changes transmission white light continuum derived photonic crystal fiber produce broadband femtosecond nanodisk. We also compare performance same measurements single-element photodiode find comparable sensitivities. The thus provides major advantage due its ability multiplex spectral detection, which utilize here capture both electronic vibrations following laser excitation.