Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Hole Scavenging and Photo-Stimulated Recombination of Electron-Hole
  Pairs in Aqueous TiO2 Nanoparticles   It is shown that 532 nm and 1064 nm laser photoexcitation of trapped
electrons generated by 355 nm photolysis of aqueous titania (TiO2)
nanoparticles causes rapid photobleaching of their absorbance band in the
visible and near IR. This photobleaching occurs within the duration of the
laser pulse (3 ns FWHM); it is caused by photoinduced electron detrapping
followed by rapid recombination of the resulting free electron and a trapped
hole. The quantum yield for the electron photobleaching is ca. 0.28 for 532 nm
and ca. 0.024 for 1064 nm photoexcitation. Complete separation of the spectral
contributions from trapped electron and hole is demonstrated using glycerol as
a selective hole scavenger. When glycerol is added to the solution, some
light-absorbing holes are scavenged promptly within the duration of the 355 nm
photoexcitation pulse, some are scavenged at a slower rate over the first 200
ns after the 355 nm pulse, and the rest are not scavenged, even at high
concentration of the scavenger (> 10 vol %). A reaction with chemi- and physi-
sorbed glycerol would account for the prompt and the slow hole decay,
respectively. The implications of these results are discussed.

1
The categories of this paper are: cs
27
The categories of this paper are: comp-gas
26
The categories of this paper are: bayes-an
29
The categories of this paper are: funct-an
35
The categories of this paper are: mtrl-th
30
The categories of this paper are: q-alg
15
The categories of this paper are: nucl-ex
22
The categories of this paper are: chao-dyn
33
The categories of this paper are: plasm-ph
0
The categories of this paper are: hep-ph
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The categories of this paper are: hep-th
8
The categories of this paper are: hep-ex
12
The categories of this paper are: nucl-th
36
The categories of this paper are: cmp-lg
14
The categories of this paper are: math-ph
28
The categories of this paper are: alg-geom