Cathodes for Electron Microscopy and Lithography

Kruit, P.

doi:10.1007/978-3-030-47291-7_6

Cited by 4 publications

(3 citation statements)

References 53 publications

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“…Of course, while the emission of electrons is largely stochastic in nature when not under ultrafast conditions, the beam can be considered as continuous over longer acquisition times. 43 , 45 , 46 , 47 …”

Section: Discussionmentioning

confidence: 99%

Design of an ultrafast pulsed ponderomotive phase plate for cryo-electron tomography

Fitzpatrick

2023

Cell Reports Methods

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Section: Discussionmentioning

confidence: 99%

Design of an ultrafast pulsed ponderomotive phase plate for cryo-electron tomography

Fitzpatrick

2023

Cell Reports Methods

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“…As a result, the most ideal condition for the ponderomotive force to occur would be in the native unmodified electron beam. Of course, while the emission of electrons is largely stochastic in nature when not under ultrafast conditions, the beam can be considered as continuous over longer acquisition times (39,(42)(43)(44).…”

Section: Stochastic/uniform Electron Emissionmentioning

confidence: 99%

Design of an ultrafast pulsed ponderomotive phase plate for cryo-electron tomography

Fitzpatrick

2022

Preprint

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Ponderomotive phase plates have shown temporally consistent phase contrast is possible within electron microscopes via high fluence static laser modes resonating in Fabry-Perot cavities. Here, we explore using pulsed laser beams as an alternative method of generating high fluences. We find through forward-stepping finite element models that picosecond-or-less interactions are required for meaningful fluences phase shifts, with higher pulse energies and smaller beam waists leading to the predicted higher fluences. An additional model based on quasiclassical assumptions is used to discover the shape of the phase plate by incorporating the oscillatory nature of the electric field. From these results, we find the transient nature of the laser pulses removes the influence of Kapitza-Dirac diffraction patterns that appear in the static resonator cases. The addition of a second laser aligned 90° to the first induces anisotropy to the shape of the phase plate. By incorporating a shifting-electron-beam algorithm, the effects of a finite electron beam crossover are also simulated. A total pulse energy of 8.7 μJ is enough to induce the required π/2 phase shift for Zernike-like phase microscopy. As a brief thought experiment, we also explore the usage of high frequency lasers in a standard electron emission scheme to see if a pulsed electron beam is even necessary. Ultimately, frequency requirements limit the laser to nanosecond pulse durations, causing the required pulse energies to reach unreasonable levels before adequate phase shifts are achieved.

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“…The REELS application inside an SEM requires that the analyzer attachment energy resolution be smaller than the energy spread of the primary electron beam. Therefore, the energy resolution needs to be below 0.5 eV for SEMs that use a thermal field emission Schottky source and be better than 0.3 eV for SEMs that use a cold field emission source [19]. Assuming that the SEM will be operated in a low voltage mode of operation, where the primary beam landing energy is typically 1 keV or below, the relative energy resolution of the REELS toroidal energy analyzer attachment, therefore, needs to be better than 0.05%.…”

Section: Introductionmentioning

confidence: 99%

The Design of a Reflection Electron Energy Loss Spectrometer Attachment for Low Voltage Scanning Electron Microscopy

Chuah

Khursheed

2021

Materials

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This paper presents the design of a reflection electron energy spectrometer (REELS) attachment for low voltage scanning electron microscopy (LVSEM) applications. The design is made by carrying out a scattered electron trajectory ray paths simulation. The spectrometer attachment is small enough to fit on the specimen stage of an SEM, and aims to acquire nanoscale spatially resolved REELS information. It uses a retarding field electrostatic toroidal sector energy analyzer design, which is able to lower the kinetic energies of elastically backscattered electrons to pass energies of 10 eV or less. For the capture of 1 keV BSEs emitted in the polar angular range between 40 to 50°, direct ray-tracing simulations predict that the spectrometer attachment will have an energy resolution of around 0.4 eV at a pass energy of 10 eV, and 0.2 eV at a pass energy of 5 eV. This predicted performance will make it a suitable REELS attachment for SEMs that use field emission electron sources.

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Cathodes for Electron Microscopy and Lithography

Cited by 4 publications

References 53 publications

Design of an ultrafast pulsed ponderomotive phase plate for cryo-electron tomography

Design of an ultrafast pulsed ponderomotive phase plate for cryo-electron tomography

Design of an ultrafast pulsed ponderomotive phase plate for cryo-electron tomography

The Design of a Reflection Electron Energy Loss Spectrometer Attachment for Low Voltage Scanning Electron Microscopy

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