Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Photophysical characterizations of 2-(4-Biphenylyl)-5 phenyl-1,3,4-
  oxadiazole in restricted geometry   Langmuir and Langmuir-Blodgett (LB) films of nonamphiphilic
2-(4-Biphenylyl)-5 phenyl-1,3,4- oxadiazole (abbreviated as PBD) mixed with
stearic acid (SA) as well as also with the inert polymer matrix poly(methyl
methacrylate) (PMMA) have been studied. Surface pressure versus area per
molecule (-A) isotherms studies suggest that PBD molecules very likely stand
vertically on the air-water interface and this arrangement allows the PBD
molecules to form stacks and remain sandwiched between SA/PMMA molecules. At
lower surface pressure phase separation between PBD and matrix molecules occur
resulting due to repulsive interaction. However at higher surface pressure PBD
molecules form aggregates. The UV-Vis absorption and Steady state fluorescence
spectroscopic studies of the mixed LB films of PBD reveal the nature of the
aggregates. H-type aggregates predominates in the mixed LB films whereas I-type
aggregates predominates in the PBD-PMMA spin coated films. The degree of
deformation produced in the electronic levels are largely affected by the film
thickness and the surface pressure of lifting.

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The categories of this paper are: q-alg
1
The categories of this paper are: cs
35
The categories of this paper are: mtrl-th
28
The categories of this paper are: alg-geom
18
The categories of this paper are: econ
24
The categories of this paper are: dg-ga
21
The categories of this paper are: adap-org
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The categories of this paper are: atom-ph
31
The categories of this paper are: ao-sci
5
The categories of this paper are: gr-qc
3
The categories of this paper are: physics
8
The categories of this paper are: hep-ex
15
The categories of this paper are: nucl-ex
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The categories of this paper are: supr-con
36
The categories of this paper are: cmp-lg
27
The categories of this paper are: comp-gas