Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Ultrafast field-driven monochromatic photoemission from carbon nanotubes   Ultrafast electron pulses, combined with laser-pump and electron-probe
technologies, allow for various forms of ultrafast microscopy and spectroscopy
to elucidate otherwise challenging to observe physical and chemical
transitions. However, the pursuit of simultaneous ultimate spatial and temporal
resolution has been largely subdued by the low monochromaticity of the electron
pulses and their poor phase synchronization to the optical excitation pulses.
State-of-the-art photon-driven sources have good monochromaticity but poor
phase synchronization. In contrast, field-driven photoemission has much higher
light phase synchronization, due to the intrinsic sub-cycle emission dynamics,
but poor monochromaticity. Such sources suffer from larger electron energy
spreads (3 - 100 eV) attributed to the relatively low field enhancement of the
conventional metal tips which necessitates long pump wavelengths (> 800 nm) in
order to gain sufficient ponderomotive potential to access the field-driven
regime. In this work, field-driven photoemission from ~1 nm radius carbon
nanotubes excited by a femtosecond laser at a short wavelength of 410 nm has
been realized. The energy spread of field-driven electrons is effectively
compressed to 0.25 eV outperforming all conventional ultrafast electron
sources. Our new nanotube-based ultrafast electron source opens exciting
prospects for attosecond imaging and emerging light-wave electronics.

17
The categories of this paper are: q-fin
16
The categories of this paper are: stat
8
The categories of this paper are: hep-ex
6
The categories of this paper are: astro-ph
27
The categories of this paper are: comp-gas
2
The categories of this paper are: math
25
The categories of this paper are: patt-sol
0
The categories of this paper are: hep-ph
33
The categories of this paper are: plasm-ph
14
The categories of this paper are: math-ph
11
The categories of this paper are: hep-lat
37
The categories of this paper are: supr-con
1
The categories of this paper are: cs
5
The categories of this paper are: gr-qc
9
The categories of this paper are: nlin
35
The categories of this paper are: mtrl-th