{"id":{"repo_id":"uiuc","oai_identifier":"oai:www.ideals.illinois.edu:2142/105787"},"canonical_url":"https://search.dev.ndltd.org/etd/uiuc/oai:www.ideals.illinois.edu:2142/105787","repository":{"repo_id":"uiuc","name":"University of Illinois - Urbana-Champaign","base_url":"https://www.ideals.illinois.edu/oai-pmh"},"display":{"title":"Transient extreme ultraviolet spectroscopy of semiconductors","abstract":"Transient extreme ultraviolet (XUV) spectroscopy is used to investigate ultrafast photophysics in lead iodide (PbI2) and methylammonium lead iodide perovskite (MAPbI3). Sub-30 fs pulses of XUV light are produced to use as a probe in a tabletop instrument using high-harmonic generation. PbI2 and MAPbI3 both absorb XUV radiation at the iodine N4,5 edge, which arises from transitions from the core I 4d orbitals to the valence and conduction bands of the semiconductor materials. Static measurements at this edge probe the iodine partial density of states of the conduction band, showing good agreement with spectra predicted using density functional theory (DFT). Excitation in the visible promotes electrons from the valence bands to the conduction bands, resulting in photogenerated charge carriers (holes and electrons). The XUV valence band region shows new transitions from the core states into the unoccupied holes, providing a tool for understanding hole dynamics in semiconductor materials. The transient signals in the XUV conduction band region result from a combination of state-blocking (band-filling) and band-gap renormalization. This can be disentangled but will require further theoretical modeling to fully extract electron dynamics. XUV and optical transient absorption (OTA) together reveal unequal cooling in MAPbI3, with the initial excitation giving more excess energy to the hole distribution than the electron distribution. The distributions show rapid cooling by carrier-phonon coupling in the first few hundred fs followed by slow cooling due to the hot-phonon bottleneck effect for tens to hundreds of ps. The cooling dynamics differ, indicating that the electron-phonon and hole-phonon coupling pathways are independent. Additional modeling and DFT prediction are used to better understand fitting OTA data to extract carrier distributions with unequal energy in each band. It is shown that OTA is more sensitive to the lower energy carrier, or to the lighter carrier for unequal effective masses.","abstract_html":"Transient extreme ultraviolet (XUV) spectroscopy is used to investigate ultrafast photophysics in lead iodide (PbI2) and methylammonium lead iodide perovskite (MAPbI3). Sub-30 fs pulses of XUV light are produced to use as a probe in a tabletop instrument using high-harmonic generation. PbI2 and MAPbI3 both absorb XUV radiation at the iodine N4,5 edge, which arises from transitions from the core I 4d orbitals to the valence and conduction bands of the semiconductor materials. Static measurements at this edge probe the iodine partial density of states of the conduction band, showing good agreement with spectra predicted using density functional theory (DFT). Excitation in the visible promotes electrons from the valence bands to the conduction bands, resulting in photogenerated charge carriers (holes and electrons). The XUV valence band region shows new transitions from the core states into the unoccupied holes, providing a tool for understanding hole dynamics in semiconductor materials. The transient signals in the XUV conduction band region result from a combination of state-blocking (band-filling) and band-gap renormalization. This can be disentangled but will require further theoretical modeling to fully extract electron dynamics. XUV and optical transient absorption (OTA) together reveal unequal cooling in MAPbI3, with the initial excitation giving more excess energy to the hole distribution than the electron distribution. The distributions show rapid cooling by carrier-phonon coupling in the first few hundred fs followed by slow cooling due to the hot-phonon bottleneck effect for tens to hundreds of ps. The cooling dynamics differ, indicating that the electron-phonon and hole-phonon coupling pathways are independent. Additional modeling and DFT prediction are used to better understand fitting OTA data to extract carrier distributions with unequal energy in each band. It is shown that OTA is more sensitive to the lower energy carrier, or to the lighter carrier for unequal effective masses.","abstract_has_math":false,"creators":["Verkamp, Max Andrew"],"institution":"University of Illinois at Urbana-Champaign","degree_name":"Ph.D.","degree_level":"Dissertation","degree_discipline":"Chemical Physics","degree_department":null,"school":null,"contributors":["Vura-Weis, Josh","Dlott, Dana D","Schleife, André","Abbamonte, Peter"],"advisors":[],"committee_chairs":[],"committee_members":[],"year":2019,"date_issued":"2019-11-26T20:49:21Z","date_published":"2019-11-26T20:49:21Z","updated_at":"2026-07-22T22:24:45Z","subjects":["extreme ultraviolet spectroscopy","perovskite","photovoltaics","carrier dynamics"],"languages":["en"],"rights":["Copyright 2019 Max Verkamp"],"rights_urls":[],"identifier_entries":[]},"links":{"outbound_url":"http://hdl.handle.net/2142/105787","outbound_label":"Handle","outbound_source":"dc:identifier"},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:contributor","label":"Contributor","values":["Vura-Weis, Josh","Dlott, Dana D","Schleife, André","Abbamonte, Peter"]},{"key":"dc:creator","label":"Author","values":["Verkamp, Max Andrew"]}]},{"id":"academic_context","label":"Academic Context","entries":[{"key":"dc:date","label":"Dc Date","values":["2019-11-26T20:49:21Z","2021-11-27T10:15:33Z","2019-07-08","2019-08"]},{"key":"dc:type","label":"Dc Type","values":["text"]},{"key":"thesis:degree_discipline","label":"Discipline","values":["Chemical Physics"]},{"key":"thesis:degree_level","label":"Degree Level","values":["Dissertation"]},{"key":"thesis:degree_name","label":"Degree Name","values":["Ph.D."]},{"key":"thesis:institution_name","label":"Thesis Institution Name","values":["University of Illinois at Urbana-Champaign"]}]},{"id":"subjects_keywords","label":"Subjects and Keywords","entries":[{"key":"dc:subject","label":"Dc Subject","values":["extreme ultraviolet spectroscopy","perovskite","photovoltaics","carrier dynamics"]}]},{"id":"language_rights","label":"Language and Rights","entries":[{"key":"dc:language","label":"Dc Language","values":["en"]},{"key":"dc:rights","label":"Dc Rights","values":["Copyright 2019 Max Verkamp"]}]},{"id":"identifiers","label":"Identifiers","entries":[{"key":"dc:identifier","label":"Identifier","values":["http://hdl.handle.net/2142/105787"]}]},{"id":"additional","label":"Additional Metadata","entries":[{"key":"dc:description","label":"Description","values":["Transient extreme ultraviolet (XUV) spectroscopy is used to investigate ultrafast photophysics in lead iodide (PbI2) and methylammonium lead iodide perovskite (MAPbI3). Sub-30 fs pulses of XUV light are produced to use as a probe in a tabletop instrument using high-harmonic generation. PbI2 and MAPbI3 both absorb XUV radiation at the iodine N4,5 edge, which arises from transitions from the core I 4d orbitals to the valence and conduction bands of the semiconductor materials. Static measurements at this edge probe the iodine partial density of states of the conduction band, showing good agreement with spectra predicted using density functional theory (DFT). Excitation in the visible promotes electrons from the valence bands to the conduction bands, resulting in photogenerated charge carriers (holes and electrons). The XUV valence band region shows new transitions from the core states into the unoccupied holes, providing a tool for understanding hole dynamics in semiconductor materials. The transient signals in the XUV conduction band region result from a combination of state-blocking (band-filling) and band-gap renormalization. This can be disentangled but will require further theoretical modeling to fully extract electron dynamics. XUV and optical transient absorption (OTA) together reveal unequal cooling in MAPbI3, with the initial excitation giving more excess energy to the hole distribution than the electron distribution. The distributions show rapid cooling by carrier-phonon coupling in the first few hundred fs followed by slow cooling due to the hot-phonon bottleneck effect for tens to hundreds of ps. The cooling dynamics differ, indicating that the electron-phonon and hole-phonon coupling pathways are independent. Additional modeling and DFT prediction are used to better understand fitting OTA data to extract carrier distributions with unequal energy in each band. It is shown that OTA is more sensitive to the lower energy carrier, or to the lighter carrier for unequal effective masses.","Submission published under a 24 month embargo labeled 'U of I Access', the embargo will last until 2021-08-01","The student, Max Verkamp, accepted the attached license on 2019-07-05 at 13:27.","The student, Max Verkamp, submitted this Dissertation for approval on 2019-07-05 at 13:47.","This Dissertation was approved for publication on 2019-07-08 at 11:25.","DSpace SAF Submission Ingestion Package generated from Vireo submission #14177 on 2019-11-26 at 13:04:31","Made available in DSpace on 2019-11-26T20:49:21Z (GMT). No. of bitstreams: 2 VERKAMP-DISSERTATION-2019.pdf: 2729590 bytes, checksum: bfcc06bd4f1d538645c4ab64ffa40de9 (MD5) LICENSE.txt: 4208 bytes, checksum: ab556f8a4a7be15a8a966839141ee874 (MD5) Previous issue date: 2019-07-08","Embargo set by: Seth Robbins for item 112932 Lift date: 2021-11-26T20:49:41Z Reason: Author requested U of Illinois access only (OA after 2yrs) in Vireo ETD system","U of I Only Restriction Lifted for Item 112932 on 2021-11-27T10:15:33Z."]},{"key":"dc:format","label":"Dc Format","values":["application/pdf"]},{"key":"dc:title","label":"Title","values":["Transient extreme ultraviolet spectroscopy of semiconductors"]}]}],"canonical_facts":{"dc:contributor":["Vura-Weis, Josh","Dlott, Dana D","Schleife, André","Abbamonte, Peter"],"dc:creator":["Verkamp, Max Andrew"],"dc:date":["2019-11-26T20:49:21Z","2021-11-27T10:15:33Z","2019-07-08","2019-08"],"dc:description":["Transient extreme ultraviolet (XUV) spectroscopy is used to investigate ultrafast photophysics in lead iodide (PbI2) and methylammonium lead iodide perovskite (MAPbI3). Sub-30 fs pulses of XUV light are produced to use as a probe in a tabletop instrument using high-harmonic generation. PbI2 and MAPbI3 both absorb XUV radiation at the iodine N4,5 edge, which arises from transitions from the core I 4d orbitals to the valence and conduction bands of the semiconductor materials. Static measurements at this edge probe the iodine partial density of states of the conduction band, showing good agreement with spectra predicted using density functional theory (DFT). Excitation in the visible promotes electrons from the valence bands to the conduction bands, resulting in photogenerated charge carriers (holes and electrons). The XUV valence band region shows new transitions from the core states into the unoccupied holes, providing a tool for understanding hole dynamics in semiconductor materials. The transient signals in the XUV conduction band region result from a combination of state-blocking (band-filling) and band-gap renormalization. This can be disentangled but will require further theoretical modeling to fully extract electron dynamics. XUV and optical transient absorption (OTA) together reveal unequal cooling in MAPbI3, with the initial excitation giving more excess energy to the hole distribution than the electron distribution. The distributions show rapid cooling by carrier-phonon coupling in the first few hundred fs followed by slow cooling due to the hot-phonon bottleneck effect for tens to hundreds of ps. The cooling dynamics differ, indicating that the electron-phonon and hole-phonon coupling pathways are independent. Additional modeling and DFT prediction are used to better understand fitting OTA data to extract carrier distributions with unequal energy in each band. It is shown that OTA is more sensitive to the lower energy carrier, or to the lighter carrier for unequal effective masses.","Submission published under a 24 month embargo labeled 'U of I Access', the embargo will last until 2021-08-01","The student, Max Verkamp, accepted the attached license on 2019-07-05 at 13:27.","The student, Max Verkamp, submitted this Dissertation for approval on 2019-07-05 at 13:47.","This Dissertation was approved for publication on 2019-07-08 at 11:25.","DSpace SAF Submission Ingestion Package generated from Vireo submission #14177 on 2019-11-26 at 13:04:31","Made available in DSpace on 2019-11-26T20:49:21Z (GMT). No. of bitstreams: 2 VERKAMP-DISSERTATION-2019.pdf: 2729590 bytes, checksum: bfcc06bd4f1d538645c4ab64ffa40de9 (MD5) LICENSE.txt: 4208 bytes, checksum: ab556f8a4a7be15a8a966839141ee874 (MD5) Previous issue date: 2019-07-08","Embargo set by: Seth Robbins for item 112932 Lift date: 2021-11-26T20:49:41Z Reason: Author requested U of Illinois access only (OA after 2yrs) in Vireo ETD system","U of I Only Restriction Lifted for Item 112932 on 2021-11-27T10:15:33Z."],"dc:format":["application/pdf"],"dc:identifier":["http://hdl.handle.net/2142/105787"],"dc:language":["en"],"dc:rights":["Copyright 2019 Max Verkamp"],"dc:subject":["extreme ultraviolet spectroscopy","perovskite","photovoltaics","carrier dynamics"],"dc:title":["Transient extreme ultraviolet spectroscopy of semiconductors"],"dc:type":["text"],"thesis:degree_discipline":["Chemical Physics"],"thesis:degree_level":["Dissertation"],"thesis:degree_name":["Ph.D."],"thesis:institution_name":["University of Illinois at Urbana-Champaign"]},"updated_at":"2026-07-22T22:24:45Z"}