Attosecond transient absorption experiments in poly(3-hexylthiophene) targets
File(s)
Author(s)
Miseikis, Lukas
Type
Thesis
Abstract
In this thesis I present the development of a new type of experiment that extends the avenues
of common time resolved measurements in the attosecond science field. The work presented
here brings the tools of attosecond science to study electron dynamics in the systems that are
the central topic in plastic electronics. A new experimental scheme is designed to study exciton
formation and evolution in organic semiconductor Poly(3-HexylThiophene) (P3HT) that is used
in organic solar cells. A variation of attosecond transient absorption spectroscopy was proposed
to study the dynamics. The challenges of this experimental arrangement were to prepare
the correct laser targets and both pump and probe pulses.
Here I present the development of solid state polymer targets that were used for the transient
absorption experiments. These targets have been succesfully prepared as free standing films in
the range of 50 nm - 200 nm thickness and their X-ray absorption spectra were measured.
Carrier envelope phase stable laser pulses centered at 1750 nm were achieved in a few optical
cycle regime via Hollow Core Fiber (HCF) compression scheme developed in house. These
pulses were used to drive High Harmonic Generation (HHG) beyond the 160 eV energy range
in a differentially pumped Ne gas target. Strong CEP dependent half cycle cutoofs were observed
in the HHG spectra confirming isolated attosecond pulses. X-ray absorption spectrum in
P3HT targets was measured using this new source.
Two routes for the optical pump generation have been explored. 17 fs, 2 mJ pulse was obtained
from the 1750 nm driver via the cascaded third harmonic generation process in a non linear
crystal and characterised using the SHG-FROG technique. This pulse was implemented as an
optical pump in the transient absorption experiment.
An interferometric optical setup was constructed that combines both the pump and the probe
generation and the delay control between them. The setup was used to obtain the initial transient
absorption experiment data.
of common time resolved measurements in the attosecond science field. The work presented
here brings the tools of attosecond science to study electron dynamics in the systems that are
the central topic in plastic electronics. A new experimental scheme is designed to study exciton
formation and evolution in organic semiconductor Poly(3-HexylThiophene) (P3HT) that is used
in organic solar cells. A variation of attosecond transient absorption spectroscopy was proposed
to study the dynamics. The challenges of this experimental arrangement were to prepare
the correct laser targets and both pump and probe pulses.
Here I present the development of solid state polymer targets that were used for the transient
absorption experiments. These targets have been succesfully prepared as free standing films in
the range of 50 nm - 200 nm thickness and their X-ray absorption spectra were measured.
Carrier envelope phase stable laser pulses centered at 1750 nm were achieved in a few optical
cycle regime via Hollow Core Fiber (HCF) compression scheme developed in house. These
pulses were used to drive High Harmonic Generation (HHG) beyond the 160 eV energy range
in a differentially pumped Ne gas target. Strong CEP dependent half cycle cutoofs were observed
in the HHG spectra confirming isolated attosecond pulses. X-ray absorption spectrum in
P3HT targets was measured using this new source.
Two routes for the optical pump generation have been explored. 17 fs, 2 mJ pulse was obtained
from the 1750 nm driver via the cascaded third harmonic generation process in a non linear
crystal and characterised using the SHG-FROG technique. This pulse was implemented as an
optical pump in the transient absorption experiment.
An interferometric optical setup was constructed that combines both the pump and the probe
generation and the delay control between them. The setup was used to obtain the initial transient
absorption experiment data.
Version
Open Access
Date Issued
2017-10
Date Awarded
2018-06
Copyright Statement
Attribution NoDerivatives 4.0 International Licence (CC BY-ND)
Advisor
Marangos, Jon
Sponsor
Engineering and Physical Sciences Research Council
Grant Number
EP-L504786-1
Publisher Department
Physics
Publisher Institution
Imperial College London
Qualification Level
Doctoral
Qualification Name
Doctor of Philosophy (PhD)