H7844

In the all-optical modulation
experiment, the control and seed light pulses (2 kHz repetition rate)
are generated by an optical parametric amplifier (Spectra-Physics,
TOPAS) and divided into two parts using a dichroic mirror. The pulse
duration of both control and seed pulses is ∼230 fs. The seed
light goes through an optical delay line and is then combined with
the control light by using another dichroic mirror (see Figure S1 in the SI). The combined beams are
focused on the sample by a 40× objective of NA 0.75. The full-width-at-half-maximum
beam diameters of the control light at 400 nm (800 nm) and the seed
light are ∼2.5 and ∼2.2 μm, respectively. The
generated SHG signal is then collected by a monochromator (Andor 328i).
Different filters are used to remove the control and seed light before
the monochromator. A photomultiplier tube (PMT, H7844 Hamamatsu) connected
to a lock-in amplifier is used to detect and monitor the SHG signal.
To calibrate the photon energy dependence, we extract the data after
considering the whole system loss within the broad range of used photon
energies and the optical reflectance/absorption of both MoS₂ and the substrate.

NP locations were observed under 980 nm NIR light and electron beam irradiation. Each type of NP was dispersed on a 50 nm-thick silicon nitride membrane grid (SN100-A50Q33, SPI Supplies). Bright-field and NIRL images were obtained with a modified laser scanning microscope (C1, Nikon) equipped with a 980 nm NIR diode laser and a photomultiplier tube (H7844 or H10330B-75, Hamamatsu) as shown in Fig. S3. NIRL images were constructed by raster scanning using a galvano mirror. After NIRL imaging, CL images were obtained with the FE-SEM-CL system described in our previous study17 (link). The emitted CL was directed to a spectrometer (TRIAX-320, Horiba-Jobin Yvon) and CL images were recorded with a photomultiplier tube-type detector (PMT, R943-02, Hamamatsu).