Watching electrons using extreme ultraviolet light

phys.org | 10/6/2014 | Staff
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A new technique developed by a team at MIT can map the complete electronic band structure of materials at high resolution. This capability is usually exclusive to large synchrotron facilities, but now it is available as a tabletop laser-based setup at MIT. This technique, which uses extreme ultraviolet (XUV) laser pulses to measure the dynamics of electrons via angle-resolved photoemission spectroscopy (ARPES), is called time-resolved XUV ARPES.

Unlike the synchrotron-based setup, this laser-based setup further provides a time-resolved feature to watch the electrons inside a material on a very fast, femtosecond (quadrillionth of a second) timescale. Comparing this fast technique on a time and distance scale, while light can travel from the moon to the Earth in roughly one second, it can only travel as far as the thickness of a single sheet of regular copy paper in one femtosecond.

MIT - Team - Resolution - Materials - Spectrum

The MIT team evaluated their instrument resolution using four exemplary materials representing a wide spectrum of quantum materials: a topological Weyl semimetal, a high-critical-temperature superconductor, a layered semiconductor, and a charge density wave system.

The technique is described in a paper appearing in the journal Nature Communications, authored by MIT physicists Edbert Jarvis Sie Ph.D. '17, former postdoc Timm Rohwer, Changmin Lee Ph.D. '18, and MIT physics Professor Nuh Gedik.

Goal - Physics - Phases - Matter - Control

A central goal of modern condensed-matter physics is to discover novel phases of matter and exert control over their intrinsic quantum properties. Such behaviors are rooted in the way the energy of electrons changes as a function of their momentum inside different materials. This relationship is known as the electronic band structure of materials and can be measured using photoemission spectroscopy. This technique uses light with high photon energy to knock the electrons away from the material surface—a process formerly known as the photoelectric effect, for which Albert Einstein received the Nobel Prize in...
(Excerpt) Read more at: phys.org
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