Characterizing the energy resolution of Bloch beamline.
(2020) FYSM30 20201Synchrotron Radiation Research
Department of Physics
- Abstract
- The Bloch beamline on 1.5 GeV ring at MAX IV Laboratory is dedicated to measure electronic structure of materials using the technique angle resolved photoelectron spectroscopy (ARPES) and spin resolved photoelectron spectroscopy (spin-ARPES). The main goal of the thesis is to experimentally determine, the energy resolution of the Bloch beamline at 21 eV and 62 eV as a function of the exit slit opening using total ion measurements. To achieve this, one has to first make sure that there was no roll misalignment of the grating. The reason being, if there is a roll misalignment, the beam exiting from the monochromator will move sideways when the grating pitch is changed to choose different energies. This sideway motion has to be then... (More)
- The Bloch beamline on 1.5 GeV ring at MAX IV Laboratory is dedicated to measure electronic structure of materials using the technique angle resolved photoelectron spectroscopy (ARPES) and spin resolved photoelectron spectroscopy (spin-ARPES). The main goal of the thesis is to experimentally determine, the energy resolution of the Bloch beamline at 21 eV and 62 eV as a function of the exit slit opening using total ion measurements. To achieve this, one has to first make sure that there was no roll misalignment of the grating. The reason being, if there is a roll misalignment, the beam exiting from the monochromator will move sideways when the grating pitch is changed to choose different energies. This sideway motion has to be then compensated by changing the pitch angle of the optical element after the monochromator.
The first part of the work is to characterize, the pitch change required of the above mentioned optical element after the monochromator as a function of the grating pitch, so the photon beam goes along the correct path. This data was then used to evaluate with a simple model the grating roll error based on the relationship between pitch angle correction of the mentioned optical element and the grating pitch angle. The validity of the model was checked with a ray tracing method before correcting for the grating misalignment. After re-alignment (by the beamline staff), the beam movement was negligible and one could proceed with the experiment to determine the beamline energy resolution at 21 eV and 62 eV using total ion yield measurements. (Less) - Popular Abstract
- In today’s scenario it is important to know about the materials around us. We try to know how one creates new materials with breathtaking properties. It is of great interest to understand the nature of their surface and how they interact with the environment.
Photoelectron spectroscopy is a powerful shining star for studying solid state physics. An example of such an interaction is corrosion - a process that is not yet completely understood on a molecular level. To get rid of corrosion, one needs to know what elements are present in the material and how they affect the process. We are helping the engineer by providing surface analysis that informs them how to design better products. Using photoelectron spectroscopy, we can obtain the... (More) - In today’s scenario it is important to know about the materials around us. We try to know how one creates new materials with breathtaking properties. It is of great interest to understand the nature of their surface and how they interact with the environment.
Photoelectron spectroscopy is a powerful shining star for studying solid state physics. An example of such an interaction is corrosion - a process that is not yet completely understood on a molecular level. To get rid of corrosion, one needs to know what elements are present in the material and how they affect the process. We are helping the engineer by providing surface analysis that informs them how to design better products. Using photoelectron spectroscopy, we can obtain the chemical composition of the surface of materials.
To analyze the surface, photoemission is processed by irradiating a sample with a photon beam. If the beam has enough energy, it will kick out electrons from an atom in the same way a football player kicks a football. Now by detecting these electrons at a detector, one can measure their kinetic energy (speed of football) as well as different angles gives different momentum of the ejected electron. Further one can determine binding energy which is one type of force which holds electrons in an atom like the gravitational force between earth and us. Graph is recorded by analyzer over a wide range of electrons, binding energy gives a footprint of element present.
To determine, if the surface behaves like a metal or semiconductor, scientists look at the so-called valence band structure. Various properties (how they behave with the environment) are closely connected to the structure of the materials. Like graphene is the world's thinnest conducting material and when it is mixed with other material becomes strongest, therefore can be used at many purposes in day to day life. ARPES is a technique which directly measures the structure as well as finding gaps between two bands and hence a very useful tools.
Total energy resolution is a combination of photon energy resolution which comes from X-ray source and the electron energy resolution that comes from the electron analyzer. My main contribution is to characterize the photon energy resolution of the beamline which is important to make the total energy resolution of the beamline as small as possible so that one can resolve closely spaced peaks and determine the elements present accurately. (Less)
Please use this url to cite or link to this publication:
http://lup.lub.lu.se/student-papers/record/9024713
- author
- Shah, Anita LU
- supervisor
- organization
- course
- FYSM30 20201
- year
- 2020
- type
- H1 - Master's Degree (One Year)
- subject
- language
- English
- id
- 9024713
- date added to LUP
- 2020-08-03 09:36:10
- date last changed
- 2020-08-03 09:36:10
@misc{9024713,
abstract = {{The Bloch beamline on 1.5 GeV ring at MAX IV Laboratory is dedicated to measure electronic structure of materials using the technique angle resolved photoelectron spectroscopy (ARPES) and spin resolved photoelectron spectroscopy (spin-ARPES). The main goal of the thesis is to experimentally determine, the energy resolution of the Bloch beamline at 21 eV and 62 eV as a function of the exit slit opening using total ion measurements. To achieve this, one has to first make sure that there was no roll misalignment of the grating. The reason being, if there is a roll misalignment, the beam exiting from the monochromator will move sideways when the grating pitch is changed to choose different energies. This sideway motion has to be then compensated by changing the pitch angle of the optical element after the monochromator.
The first part of the work is to characterize, the pitch change required of the above mentioned optical element after the monochromator as a function of the grating pitch, so the photon beam goes along the correct path. This data was then used to evaluate with a simple model the grating roll error based on the relationship between pitch angle correction of the mentioned optical element and the grating pitch angle. The validity of the model was checked with a ray tracing method before correcting for the grating misalignment. After re-alignment (by the beamline staff), the beam movement was negligible and one could proceed with the experiment to determine the beamline energy resolution at 21 eV and 62 eV using total ion yield measurements.}},
author = {{Shah, Anita}},
language = {{eng}},
note = {{Student Paper}},
title = {{Characterizing the energy resolution of Bloch beamline.}},
year = {{2020}},
}