This widefield transient absorption microscope is designed to simultaneously acquire single wavelength transient absorption kinetics over a large area with sub-micron spatial resolution and femtosecond time-resolution. Unlike most transient absorption microscopy techniques, it does not require scanning of the sample or the laser beam.
Large area data acquisition. Transient absorption data are measured over the whole 55 x 41 μm area viewed by the camera. It facilitates fast data-acquisition over a large area with low repetition rate laser, for example, the widely used 1 kHz femtosecond laser.
Uniform light field. The area-pump and area-probe are focused through a top-hat beam shaper to make sure the field intensity on the sample is uniform. The uniformed field minimizes the heterogeneity of kinetics caused by variation in pump or probe light intensity.
High resolution. A 100X, ≥0.9 NA objective lens is used. 550 nm resolution is achieved when viewing the sample illuminated by a white light LED light source.
Two available excitation modes:
Single-spot excitation mode: only a single spot (determined by spatial resolution) on the sample is excited and the kinetics around the spot can be measured. This mode facilitates measurements of spatial dynamics, such as carrier diffusion.
Area excitation mode: an area of the sample is excited and measured evenly and simultaneously. This mode facilitates mapping of the kinetics over a large area on the sample.
Mode
Transmission
Spatial Resolution
Typically 0.5 μm (depends on the wavelength)
Spectral Range
400 – 800 nm
Observation area size
55 x 41 μm
Camera image size
640 x 480 pixels
Maximum Frame Rate
1000 Hz
Numerical Aperture
⩾ 0.9 NA
Magnification
100X
Image of 1951 USAF Resolution Test Target.
A full 55 x 41 μm area scan of MoS2 triangles probed at 2 ps after a uniform full area excitation.
Arrows indicate the location of kinetic extraction.
Kinetics of the full area excitation transient absorption microscopy of MoS2 triangles.
Single-spot excitation of a lone MoS2 flake while probing a 2.7 μm x 2.7 µm area.
Arrows indicate the location of kinetic extraction.
Kinetics of the single-spot excitation transient absorption microscopy of the MoS2 flake.
MoS2 Widefield Pump-probe Microscopy Application Note.pdf
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