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Title: Two-color field enhancement at an STM junction for spatiotemporally resolved photoemission

Here, we report measurements and numerical simulations of ultrafast laser-excited carrier flow across a scanning tunneling microscope (STM) junction. The current from a nanoscopic tungsten tip across a ~1 nm vacuum gap to a silver surface is driven by a two-color excitation scheme that uses an optical delay-modulation technique to extract the two-color signal from background contributions. The role of optical field enhancements in driving the current is investigated using density functional theory and full three-dimensional finite-difference time-domain computations. We find that simulated field-enhanced two-photon photoemission (2PPE) currents are in excellent agreement with the observed exponential decay of the two-color photoexcited current with increasing tip–surface separation, as well as its optical-delay dependence. The results suggest an approach to 2PPE with simultaneous subpicosecond temporal and nanometer spatial resolution.
Authors:
 [1] ;  [2] ;  [1] ;  [1] ;  [1] ;  [3] ;  [4] ;  [5]
  1. Columbia Univ., New York, NY (United States)
  2. Columbia Univ., New York, NY (United States); Univ. of Michigan, Ann Arbor, MI (United States)
  3. Brookhaven National Lab. (BNL), Upton, NY (United States); The Univ. of Texas at Austin, Austin, TX (United States)
  4. Brookhaven National Lab. (BNL), Upton, NY (United States); Univ. of Nebraska, Lincoln, NE (United States)
  5. Brookhaven National Lab. (BNL), Upton, NY (United States)
Publication Date:
Report Number(s):
BNL-114695-2017-JA
Journal ID: ISSN 0146-9592; OPLEDP; R&D Project: CO007; KC0301050
Grant/Contract Number:
SC0012704; AC02-98CH10886; FG02-90ER14104
Type:
Accepted Manuscript
Journal Name:
Optics Letters
Additional Journal Information:
Journal Volume: 42; Journal Issue: 13; Journal ID: ISSN 0146-9592
Publisher:
Optical Society of America (OSA)
Research Org:
Brookhaven National Laboratory (BNL), Upton, NY (United States)
Sponsoring Org:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
OSTI Identifier:
1409641
Alternate Identifier(s):
OSTI ID: 1367373

Meng, Xiang, Jin, Wencan, Yang, Hao, Dadap, Jerry I., Osgood, Jr., Richard M., Dolocan, Andrei, Sutter, Peter, and Camillone, III, Nicholas. Two-color field enhancement at an STM junction for spatiotemporally resolved photoemission. United States: N. p., Web. doi:10.1364/OL.42.002651.
Meng, Xiang, Jin, Wencan, Yang, Hao, Dadap, Jerry I., Osgood, Jr., Richard M., Dolocan, Andrei, Sutter, Peter, & Camillone, III, Nicholas. Two-color field enhancement at an STM junction for spatiotemporally resolved photoemission. United States. doi:10.1364/OL.42.002651.
Meng, Xiang, Jin, Wencan, Yang, Hao, Dadap, Jerry I., Osgood, Jr., Richard M., Dolocan, Andrei, Sutter, Peter, and Camillone, III, Nicholas. 2017. "Two-color field enhancement at an STM junction for spatiotemporally resolved photoemission". United States. doi:10.1364/OL.42.002651. https://www.osti.gov/servlets/purl/1409641.
@article{osti_1409641,
title = {Two-color field enhancement at an STM junction for spatiotemporally resolved photoemission},
author = {Meng, Xiang and Jin, Wencan and Yang, Hao and Dadap, Jerry I. and Osgood, Jr., Richard M. and Dolocan, Andrei and Sutter, Peter and Camillone, III, Nicholas},
abstractNote = {Here, we report measurements and numerical simulations of ultrafast laser-excited carrier flow across a scanning tunneling microscope (STM) junction. The current from a nanoscopic tungsten tip across a ~1 nm vacuum gap to a silver surface is driven by a two-color excitation scheme that uses an optical delay-modulation technique to extract the two-color signal from background contributions. The role of optical field enhancements in driving the current is investigated using density functional theory and full three-dimensional finite-difference time-domain computations. We find that simulated field-enhanced two-photon photoemission (2PPE) currents are in excellent agreement with the observed exponential decay of the two-color photoexcited current with increasing tip–surface separation, as well as its optical-delay dependence. The results suggest an approach to 2PPE with simultaneous subpicosecond temporal and nanometer spatial resolution.},
doi = {10.1364/OL.42.002651},
journal = {Optics Letters},
number = 13,
volume = 42,
place = {United States},
year = {2017},
month = {6}
}