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

Journal Article · Fri Jun 30 00:00:00 EDT 2017 · Optics Letters

DOI:https://doi.org/10.1364/OL.42.002651· OSTI ID:1409641

Meng, Xiang ^[1]; Jin, Wencan ^[2]; Yang, Hao ^[1]; Dadap, Jerry I. ^[1]; Osgood, Jr., Richard M. ^[1]; Dolocan, Andrei ^[3]; Sutter, Peter ^[4]; Camillone, III, Nicholas ^[5]

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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)

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.

• Research Organization: Brookhaven National Laboratory (BNL), Upton, NY (United States)
• Sponsoring Organization: USDOE Office of Science (SC), Basic Energy Sciences (BES)
• Grant/Contract Number: SC0012704; AC02-98CH10886; FG02-90ER14104
• OSTI ID: 1409641
• Alternate ID(s): OSTI ID: 1367373
• Report Number(s): BNL-114695-2017-JA; OPLEDP; R&D Project: CO007; KC0301050
• Journal Information: Optics Letters, Vol. 42, Issue 13; ISSN 0146-9592
• Publisher: Optical Society of America (OSA)
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY