Development of an Ambient-operating Correlative Light and Electron Microscope (airCLEM)

Professor Yin, Xiaobo   (Project Coordinator (PC))

Chen Fu Rong   (Co-Investigator)

Professor Wang Liqiu   (Co-Investigator)

Professor Yam Vivian Wing Wah   (Collaborator)

Professor Wu Jin   (Collaborator)

Professor Jiang Haibo   (Co-principal investigator)

Professor Feng Shien Ping Tony   (Co-Investigator)

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2023-06-01

7976880

Development of an Ambient-operating Correlative Light and Electron Microscope (airCLEM)

1) Electron Microscope 2) Optical Microscope 3) in situ Microscope 4) Low stress membranes 5) Electron Optics

Materials SciencesOthers - Physical Sciences

Physical Sciences (P)

C7098-22E

Collaborative Research Fund (CRF) - Group Research Project 2022/2023

2022

On-going

1. This collaborative research develops a first-of-its-kind Ambient-operating Correlative Light and Electron Microscope (airCLEM) in Hong Kong. It allows electron microscope imaging of any samples placed in the air, regardless of the sample conditions - solid or liquid, conductive or insulating, organic or inorganic, or even living systems — transforming today’s imaging and spectroscopic research for complex materials. It couples a high-end optical microscope for correlated, simultaneously collected multimodal images of cathodoluminescences and other optical and spectroscopic information with a spatial resolution determined by the focal volume of the parfocal electron beam. 2. To build an ambient-operating scanning electron microscope. Leveraging the support from the manufacturer, a field-emission electron microscope will be modified to bring the electron beam out of the electron-optics vacuum chamber through a commercially available, nanometer-think, vacuum sealing but electron permeable silicon nitride (SiN) membrane. The electron beam is focused right beneath the membrane to minimize the scattering of air molecules. The working distance is 10 – 75 um, shorter than the mean free scattering length of the 30 keV electron beam at 1-atm. The energetic backscattered electrons are collected by both an in-column and a side-mount detector to form scanning electron micrographs. The system equips a tunable voltage source and has an image resolution between 2 – 10 nm depending on the acceleration voltage and the nature of the specimens. One specially designed vacuum flange will be manufactured to fit onto the electron optics column to host the vacuum sealing SiN membrane. An isolation chamber will be introduced between the highvacuum electron-optics and the SiN membrane to protect the electron optics. Modifications to the microscope hardware and software will be done with the guidance and help of the microscope manufacturer. The ambient-operating electron microscope will remove all major constraints that a conventional vacuum-based electron beam tool imposed on samples. It permits fully hydrated samples and allows imaging at liquid-air interfaces even with reactive mass transfers. 3. To integrate a colocalized optical spectroscopy and microscope system with the ambientoperating electron microscope, which enables multiple imaging modalities that are complementary to the backscattering images of the scanning electron beams. The line-scan and the frame-scan synchronisation signals of the scanning electron optics will be used to trigger/synchronise the acquisition of optical signals, forming colocalized images. A set of multi-channel luminescence/fluorescence detectors will be used to detect visible and nearinfrared emissions from the confocal volume of the focused electron beam, allowing cathodoluminescence images with deep-sub-diffraction-limit spatial resolutions. The in-line configuration of the electron optics and the underneath microscope optics avoids the typically used parabolic mirrors in a vacuum-based cathodoluminescence microscope, which has a limited numerical aperture and tremendous constraints for samples. The aberration-free spectrometer equips Fourier-transforming optics for direct mapping of optical dispersion of photonic nanostructures and optoelectronic materials. 4. To explore the scientific frontiers enabled by the unique capabilities of the airCLEM. This includes but is not limited to the following, to study fully hydrated samples under an electron microscope, providing a  transformative approach for research in soft matter, biology,ecology, and beyond. Samples include hydrogels, tissues, live cells, plant leaves still undergoing photosynthesis, and even fresh mice brain slices. to research nanoscale heat transfer and phase transitions on the liquid-solid and liquid-gas interfaces even with the reactive mass flow, bringing new insights on fundamental questions such as how droplets formed on surfaces (for applications of condensation and water harvesting). to in situ characterise materials when they are functioning in their native working environment, for example, battery materials in aqueous electrolyte and metal corrosions under acidic vapor.