Ultrafast Electron Microscopy Analysis

Better Essays
Ultrafast Electron Microscopy has been demonstrated to be an effective table-top technique for imaging the temporally-evolving dynamics of matter with subparticle spatial resolution on the time scale of atomic motion. A stringent enhancement of the UEM temporal resolution is demanded for recording snapshots of the electron motion which will provide a real-time access to all microscopic motions outside the atomic core and radically change our insight into the workings of the microcosm. Here, we demonstrate an order of magnitude enhancement in the temporal resolution of UEM by generation ~ 30 fs electron pulse (200 KeV) by the optical-gating approach using a visible laser pulse with the strength for probing the matter dynamics. Moreover, the …show more content…
It can be explained as follows; the ultrafast electron pulses with a duration of couple hundreds of femtosecond are generated by the photoemission process by illuminating the photocathode inside the microscope by UV laser pulses. These electron pulses are accelerated inside the microscope and incident on the sample under study together with visible laser pulses. The photon-electron coupling between the optical pulses and the electron pulses takes place when the energy-momentum conservation condition is satisfied (27, 28). This inelastic interaction leads to gain/loss of photon quanta via electron packets, which can be resolved in the electron energy spectrum consisting of discrete peaks, spectrally separated by multiples of photon energy (nћω), on both sides of the zero loss peak (ZLP). The electron that gain or loss energy due to the coupling only exists in the presence of the optical laser pulse. In another word, the optical laser pulse acts as a temporal gating of these electrons and the time window of this gating is the optical pulse duration. These gated electrons can be filtered out providing a magnificent enhancement of the temporal resolution in electron microscopy. Another optical laser pulse can be utilized to trigger the ultrafast dynamics of matter which can be envisaged by gated-electrons in different modes i.e. diffraction, electron …show more content…
At the spatiotemporal overlapping between the two pulses, the coupling between the visible and electron pulses take place. The signature of the electron-photon coupling can be revealed by measuring the electron energy spectrum by the electron energy spectrometer in the microscope. The measured electron spectrum is shown in Fig. 2A. The red white part of the spectrum represents the ZLP while blue part shows the gated electron

Related Documents

  • Decent Essays

    Gating Pulse Synthesis

    • 1722 Words
    • 7 Pages

    The visible pulse (gating pulse) enters the microscope, and together with the ultrafast electron pulses illuminate the nanostructure specimen (gold nanoparticle). The visible laser pulse kept at low power (~1.8 mJ/cm2) to avoid saturation. At the spatiotemporal overlapping, the coupling between the visible and electron pulses takes place. The signature of this coupling can be revealed by measuring the electron energy spectrum using the electron energy spectrometer attached to the microscope. The measured electron spectrum is shown in blue line curve in Fig.…

    • 1722 Words
    • 7 Pages
    Decent Essays
  • Decent Essays

    That can be resolved in the electron energy spectrum as discrete peaks on the higher and lower energy sides of the zero loss peak (ZLP) separated by multiples of photon energy (nћω) (Fig. 2b).3 In this case, the optical attosecond pulse acts as a temporal gate for the electron pulses. Therefore, the electrons that only gain energy due to the coupling (shaded area in Fig. 2b), emulate the optical attosecond pulse duration, have effectively sub-femtosecond resolution4. The optically-gated electrons are filtered out and utilized to probe and image the ultrafast electron dynamics triggered by a second optical pulse, as is schematically illustrated in Fig.…

    • 1768 Words
    • 8 Pages
    Decent Essays
  • Decent Essays

    The Atomic Model

    • 723 Words
    • 3 Pages

    This theory says that in order for an electron to orbit the nucleus of an atom, the number of wavelengths that it takes to get around must be quantized; meaning an integer number. Atoms have different energy states each with a specific energy. Photons (basic units of light) interact with electrons by giving or taking away energy. A photon with correct energy and wavelength hits an atom’s electrons, allowing the electrons to jump to a higher energy states which makes the electron “excited”. When a photon is emitted the atom drops to a lower energy state because without the energy of the photon, the electron becomes…

    • 723 Words
    • 3 Pages
    Decent Essays
  • Decent Essays

    • Powder X-ray diffraction(PXRD) • Ultraviolet –Visible spectrometry(UV) • Scanning electron microscopy(SEM) • Energy dispersive X-ray spectroscopy(EDS) 1.8.1 Powder XRD analysis (PXRD) The structural information of the prepared samples is examined through powder X-ray diffraction. X-ray crystallography is a tool, which is used to identify the crystal structure of a system. By measuring the angles and intensities of the diffraction pattern, we…

    • 1032 Words
    • 5 Pages
    Decent Essays
  • Decent Essays

    An electron vacancy is created and is further filled by an electron from the higher shell and thus an X-ray is emitted to balance the difference in energy between the two electrons. The detector placed on the energy dispersive spectroscope apparatus measures the number of emitted X-rays and their energies. Energy of the X-ray is characteristics of the element from which X-ray is emitted. A spectrum of the relative counts of the detected X-rays is obtained and evaluated for quantitative determinations of the elements present in the sample volume. In the present study, the surface morphology of the nanomaterials was obtained from SEM images using JEOL Model JSM 5600LV.…

    • 1165 Words
    • 5 Pages
    Decent Essays
  • Decent Essays

    Spectroscopy Essay

    • 1635 Words
    • 7 Pages

    Types of Spectroscopy used in Organic Chemistry 1.1 Introduction Spectroscopy is the study of the interaction between matter and light (electromagnetic radiation) (Crouch & Skoog, 2007). It is often phrased as the light of knowledge (Reusch, 2013). In the past, spectroscopy started by the study of visible light dispersed according to its wavelength by a prism (Anon., n.d.). Now, with the knowledge of light having both wave-like and particle-like characteristics, with given frequency or wavelength of light is associated with radiative energy called photon. Spectroscopy is used in physical and analytical chemistry because atoms and molecules have unique spectra (Anon., n.d.).…

    • 1635 Words
    • 7 Pages
    Decent Essays
  • Decent Essays

    X-Ray Research Paper

    • 1000 Words
    • 4 Pages

    Roentgen found that very penetrating radiations were produced from the anode, which he called x-rays. In an X-ray machine, a stream of highly charged electrons is made to strike a metal target. This arouses some of the electrons in the atoms of the target material. In the process of giving off the excess energy thus gained, the atomic electrons send out Xrays(see fig.2). The principal uses of x-rays are in the field of scientific research, industry, and medicine.…

    • 1000 Words
    • 4 Pages
    Decent Essays
  • Decent Essays

    The images in this paper were obtained by the detection of secondary electrons that were emitted by atoms excited by the primary electron beam. The primary beam scans in a raster fashion, making horizontal passes across the x-axis one at a time. This allows the detector to display the information into the image on pixel at a time in synchronized manner. The number of secondary electrons that can be detected…

    • 1149 Words
    • 5 Pages
    Decent Essays
  • Decent Essays

    Electron Microscopy Essay

    • 892 Words
    • 4 Pages

    Unlike light microscopy, TEM uses a beam of electrons, denoted as a cathode ray, to scan samples. While the traditional optical microscope is restricted in resolution by the wavelength of…

    • 892 Words
    • 4 Pages
    Decent Essays
  • Decent Essays

    The heat released from sample material due to absorption of laser radiation 2. Generation of acoustic and thermal wave from the sample material 3. Determination of PA signal in the detector HEAT RELEASE IN THE SAMPLE MATERIAL: The interaction of light with the material cause a series of effect namely excitation in the rotational, vibrational, electronic energy levels. Then from excited state, it loses energy by radiation process like spontaneous emission, stimulated emission; and by non-radiative processes which gives off heat energy. The heat released by the process can be explained by a rate equation.…

    • 931 Words
    • 4 Pages
    Decent Essays