Science Daily April 26, 2023 Researchers in Germany have shown that by superimposing two laser fields of different strengths and frequency, the electron emission of metals can be measured and controlled precisely to a few attoseconds. So far, scientists have only been able to determine laser-induced electron dynamics precisely in gases with an accuracy of a few attoseconds. Quantum dynamics and emission time windows have not yet been measured on solids. Instead of just a strong laser pulse, which emits the electrons a pointy tungsten tip, they also used a second weaker laser with twice the frequency. The electrons then […]
Tag Archives: Photoemission
Breakthrough discovery in materials science challenges current understanding of photoemission
Phys.org March 14, 2023 Currently existing photocathodes are based on conventional metals and semiconductors that were discovered six decades ago with sound theoretical underpinnings. An international team of researchers (China, Japan, USA- Northeastern University) has observed unusual photoemission properties of a reconstructed surface of SrTiO3(100) single crystals. Unlike other positive-electron-affinity (PEA) photocathodes, their PEA SrTiO3 surface produced discrete secondary photoemission spectra at room temperature, characteristic of the efficient negative-electron-affinity photocathode materials. Using several photon energies they were able to produce a very intense coherent secondary photoemission. According to the researchers the observed emergence of coherence in secondary photoemission points to […]
Enhancing photoelectric efficiency
Phys.org September 6, 2021 Researchers at Michigan State University performed a comprehensive theoretical analysis of photoemission from metal surfaces due to laser illumination ranging from ultraviolet wavelengths of 200 nanometers to near-infrared wavelengths of 1200 nanometers. By analyzing photoemission mechanisms, current density, and quantum efficiency for this range of wavelengths, they found the electron emission mechanism varies depending on the laser wavelength, laser intensity and DC bias field. The calculations showed quantum efficiency can be nonlinearly increased through electron heating produced by intense sub-picosecond laser pulses, emphasizing the importance of laser heating. Quantum efficiency increased the most at laser wavelengths […]