Time-stretched multi-hit 3D velocity map imaging of photoelectrons

The 2D photoelectron velocity map imaging (VMI) technique is commonly employed in gas-phase molecular spectroscopy and dynamics investigations due to its ability to efficiently extract photoelectron spectra and angular distributions in a single experiment. However, the standard technique is limited...

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Bibliographic Details
Published in:Review of scientific instruments 2023-06, Vol.94 (6)
Main Authors: Goudreau, E. Scott, Boguslavskiy, Andrey E., Moffatt, Douglas J., Makhija, Varun, Hemsworth, Michael, Lausten, Rune, Marceau, Claude, Wilkinson, Iain, Stolow, Albert
Format: Article
Language:English
Subjects:
Cameras
Data acquisition
Diameters
Electrode polarization
Electrons
Image reconstruction
Microchannel plates
Microchannels
Molecular spectroscopy
Phosphors
Photoelectrons
Scientific apparatus & instruments
Spatial resolution
Spectrum analysis
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Summary:The 2D photoelectron velocity map imaging (VMI) technique is commonly employed in gas-phase molecular spectroscopy and dynamics investigations due to its ability to efficiently extract photoelectron spectra and angular distributions in a single experiment. However, the standard technique is limited to specific light-source polarization geometries. This has led to significant interest in the development of 3D VMI techniques, which are capable of measuring individual electron positions and arrival times, obtaining the full 3D distribution without the need for inversion, forward-convolution, or tomographic reconstruction approaches. Here, we present and demonstrate a novel time-stretched, 13-lens 3D VMI photoelectron spectrometer, which has sub-camera-pixel spatial resolution and 210 ps (σ) time-of-flight (TOF) resolution (currently limited by trigger jitter). We employ a kHz CMOS camera to image a standard 40 mm diameter microchannel plate (MCP)/phosphor anode detector (providing x and y positions), combined with a digitizer pick-off from the MCP anode to obtain the electron TOF. We present a detailed analysis of time-space correlation under data acquisition conditions which generate multiple electrons per laser shot, and demonstrate a major advantage of this time-stretched 3D VMI approach: that the greater spread in electron TOFs permits for an accurate time- and position-stamping of up to six electrons per laser shot at a 1 kHz repetition rate.
ISSN:0034-6748
1089-7623
DOI:10.1063/5.0149897