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  1. Article ; Online: Tuning the photodynamics of sub-nanometer neutral chromium oxide clusters through sequential oxidation.

    Garcia, Jacob M / Sayres, Scott G

    Nanoscale

    2022  Volume 14, Issue 21, Page(s) 7798–7806

    Abstract: Sub-nanometer neutral chromium oxide clusters were produced in the gas phase through laser ablation and their low-lying excited state lifetimes were measured using femtosecond pump-probe spectroscopy. Time-dependent density functional theory calculations ...

    Abstract Sub-nanometer neutral chromium oxide clusters were produced in the gas phase through laser ablation and their low-lying excited state lifetimes were measured using femtosecond pump-probe spectroscopy. Time-dependent density functional theory calculations relate the trends in experimental lifetimes to the cluster's electronic structure. The photoexcited (CrO
    Language English
    Publishing date 2022-06-01
    Publishing country England
    Document type Journal Article
    ZDB-ID 2515664-0
    ISSN 2040-3372 ; 2040-3364
    ISSN (online) 2040-3372
    ISSN 2040-3364
    DOI 10.1039/d2nr00464j
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  2. Article ; Online: Orbital-dependent photodynamics of strongly correlated nickel oxide clusters.

    Garcia, Jacob M / Sayres, Scott G

    Physical chemistry chemical physics : PCCP

    2022  Volume 24, Issue 9, Page(s) 5590–5597

    Abstract: The ultrafast electronic relaxation dynamics of neutral nickel oxide clusters were investigated with femtosecond pump-probe spectroscopy and supported with theoretical calculations to reveal that their excited state lifetimes are strongly dependent on ... ...

    Abstract The ultrafast electronic relaxation dynamics of neutral nickel oxide clusters were investigated with femtosecond pump-probe spectroscopy and supported with theoretical calculations to reveal that their excited state lifetimes are strongly dependent on the nature of the electronic transition. Absorption of a UV photon produces short-lived (lifetime ∼ 110 fs) dynamics in stoichiometric (NiO)
    Language English
    Publishing date 2022-03-02
    Publishing country England
    Document type Journal Article
    ZDB-ID 1476244-4
    ISSN 1463-9084 ; 1463-9076
    ISSN (online) 1463-9084
    ISSN 1463-9076
    DOI 10.1039/d2cp00209d
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  3. Article ; Online: Increased Excited State Metallicity in Neutral Cr

    Garcia, Jacob M / Sayres, Scott G

    Journal of the American Chemical Society

    2021  Volume 143, Issue 38, Page(s) 15572–15575

    Abstract: Excited state lifetimes of neutral ... ...

    Abstract Excited state lifetimes of neutral Cr
    Language English
    Publishing date 2021-09-13
    Publishing country United States
    Document type Journal Article ; Research Support, Non-U.S. Gov't ; Research Support, U.S. Gov't, Non-P.H.S.
    ZDB-ID 3155-0
    ISSN 1520-5126 ; 0002-7863
    ISSN (online) 1520-5126
    ISSN 0002-7863
    DOI 10.1021/jacs.1c07275
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  4. Article ; Online: Oxygen Deficiencies in Titanium Oxide Clusters as Models for Bulk Defects.

    Heald, Lauren F / Garcia, Jacob M / Sayres, Scott G

    The journal of physical chemistry. A

    2022  Volume 126, Issue 2, Page(s) 211–220

    Abstract: TD-DFT calculations were performed on neutral ... ...

    Abstract TD-DFT calculations were performed on neutral Ti
    Language English
    Publishing date 2022-01-10
    Publishing country United States
    Document type Journal Article
    ISSN 1520-5215
    ISSN (online) 1520-5215
    DOI 10.1021/acs.jpca.1c07733
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  5. Article: Increased Excited State Metallicity in Neutral Cr₂Oₙ Clusters (n < 5) upon Sequential Oxidation

    Garcia, Jacob M. / Sayres, Scott G.

    Journal of the American Chemical Society. 2021 Sept. 13, v. 143, no. 38

    2021  

    Abstract: Excited state lifetimes of neutral Cr₂Oₙ (n < 5) clusters were measured using femtosecond pump–probe spectroscopy. Density functional theory calculations reveal that the excited state dynamics are correlated with changes in the cluster’s electronic ... ...

    Abstract Excited state lifetimes of neutral Cr₂Oₙ (n < 5) clusters were measured using femtosecond pump–probe spectroscopy. Density functional theory calculations reveal that the excited state dynamics are correlated with changes in the cluster’s electronic structure with increasing oxidation. Upon absorption of a UV (400 nm) photon, the clusters exhibit features attributed to three separate relaxation processes. All clusters exhibit similar subpicosecond lifetimes, attributed to vibrational relaxation. However, the ∼30 fs transient signal fraction grows linearly with oxidation, matching the amount of O to Cr charge transfer character of the photoexcitation and highlighting a gradual transition between semiconducting and metallic behavior at the molecular level. A long-lived (>2.5 ps) response is recorded only in clusters with significant d-electron character, suggesting that adiabatic relaxation back to the ground state is efficient in heavily oxidized clusters, due to the presence of terminal O atoms. The simple picture of sequential oxidation of Cr₂Oₙ reveals a linear variation in the contributions of each relaxation component to the total transient signals, therefore opening possibilities for the design of new molecular spintronic materials.
    Keywords absorption ; density functional theory ; oxidation ; photochemical reactions ; photons ; semiconductors ; spectroscopy
    Language English
    Dates of publication 2021-0913
    Size p. 15572-15575.
    Publishing place American Chemical Society
    Document type Article
    ZDB-ID 3155-0
    ISSN 1520-5126 ; 0002-7863
    ISSN (online) 1520-5126
    ISSN 0002-7863
    DOI 10.1021/jacs.1c07275
    Database NAL-Catalogue (AGRICOLA)

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  6. Article ; Online: Atom probe tomography using an extreme ultraviolet trigger pulse.

    Caplins, Benjamin W / Chiaramonti, Ann N / Garcia, Jacob M / Sanford, Norman A / Miaja-Avila, Luis

    The Review of scientific instruments

    2023  Volume 94, Issue 9

    Abstract: Atom probe tomography (APT) is a powerful materials characterization technique capable of measuring the isotopically resolved three-dimensional (3D) structure of nanoscale specimens with atomic resolution. Modern APT instrumentation most often uses an ... ...

    Abstract Atom probe tomography (APT) is a powerful materials characterization technique capable of measuring the isotopically resolved three-dimensional (3D) structure of nanoscale specimens with atomic resolution. Modern APT instrumentation most often uses an optical pulse to trigger field ion evaporation-most commonly, the second or third harmonic of a Nd laser is utilized (∼λ = 532 nm or λ = 355 nm). Herein, we describe an APT instrument that utilizes ultrafast extreme ultraviolet (EUV) optical pulses to trigger field ion emission. The EUV light is generated via a commercially available high harmonic generation system based on a noble-gas-filled capillary. The centroid of the EUV spectrum is tunable from around 25 eV (λ = 50 nm) to 45 eV (λ = 28 nm), dependent on the identity of the gas in the capillary (Xe, Kr, or Ar). EUV pulses are delivered to the APT analysis chamber via a vacuum beamline that was optimized to maximize photon flux at the APT specimen apex while minimizing complexity. We describe the design of the beamline in detail, including the various compromises involved. We characterize the spectrum of the EUV light and its evolution as it propagates through the various optical elements. The EUV focus spot size is measured at the APT specimen plane, and the effects of misalignment are simulated and discussed. The long-term stability of the EUV source has been demonstrated for more than a year. Finally, APT mass spectra are shown, demonstrating the instrument's ability to successfully trigger field ion emission from semiconductors (Si, GaN) and insulating materials (Al2O3).
    Language English
    Publishing date 2023-09-13
    Publishing country United States
    Document type Journal Article
    ZDB-ID 209865-9
    ISSN 1089-7623 ; 0034-6748
    ISSN (online) 1089-7623
    ISSN 0034-6748
    DOI 10.1063/5.0160797
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  7. Article ; Online: Analysis of Anonymous Student Narratives About Experiences with Emergency Medicine Residency Programs.

    Estes, Molly / Garcia, Jacob / Ren, Ronnie / Olaf, Mark / Moffett, Shannon / Galuska, Michael / Chi Zhang, Xiao

    The western journal of emergency medicine

    2024  Volume 25, Issue 2, Page(s) 191–196

    Abstract: Background: Academic emergency medicine (EM) communities have viewed anonymous online communities (AOC) such as Reddit or specialty-specific "applicant spreadsheets" as poor advising resources. Despite this, robust EM AOCs exist, with large user bases ... ...

    Abstract Background: Academic emergency medicine (EM) communities have viewed anonymous online communities (AOC) such as Reddit or specialty-specific "applicant spreadsheets" as poor advising resources. Despite this, robust EM AOCs exist, with large user bases and heavy readership. Insights about applicants' authentic experiences can be critical for applicants and program leadership decision-making. To date, there are no EM studies to qualitatively assess EM AOC narratives during the application cycle. Our goal was to perform a qualitative analysis of students' EM program experiences through a publicly available AOC.
    Methods: This was a qualitative analysis of a publicly available, time-stamped, user-locked AOC dataset: "Official 2020-2021 Emergency Medicine Applicant Spreadsheet." We extracted and then de-identified all data from selected sub-sheets entitled "Virtual Interview Impressions" and "Rotation Impressions." Four investigators used constant comparative method to analyze the data inductively, and they subsequently met to generate common themes discussed by students. Preliminary thematic analysis was conducted on a random sample of 37/183 (20%) independent narratives to create the initial codebook. This was used and updated iteratively to analyze the entire narrative set consisting of 841 discrete statements. Finally, two unique codes were created to distinguish whether the identified sub-themes, or program attributes, were likely "modifiable" or "non-modifiable."
    Results: We identified six major themes: living and working conditions; interpersonal relationships; learning experiences, postgraduate readiness, and online/virtual supplements. Common sub-themes included patient population (13%); resident personality (7%); program leadership personality (7%); relationship with faculty/leadership (6%); geography (4%); practice setting (4%); program reputation (4%), and postgraduate year-3 experiences (4%). Modifiable sub-themes outnumbered non-modifiable sub-themes, 60.7% to 39.3%.
    Conclusion: In this analysis of selected medical students' narratives in an AOC, the majority of identified themes represented topics that may serve as external feedback for EM residency programs and their clerkships. Selective use of AOCs may set a precedent for future program assessments by applicants and inform program leadership of important programmatic elements in the eyes of applicants. It elucidates important themes in their interactions or learning experiences with programs and creates opportunities for learner-centric program improvement.
    MeSH term(s) Humans ; Internship and Residency ; Narration ; Students, Medical ; Interpersonal Relations ; Emergency Medicine/education
    Language English
    Publishing date 2024-04-04
    Publishing country United States
    Document type Journal Article
    ZDB-ID 2375700-0
    ISSN 1936-9018 ; 1936-9018
    ISSN (online) 1936-9018
    ISSN 1936-9018
    DOI 10.5811/westjem.17973
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  8. Article ; Online: Ultrafast pump-probe spectroscopy of neutral Fe

    Garcia, Jacob M / Shaffer, Ryan E / Sayres, Scott G

    Physical chemistry chemical physics : PCCP

    2020  Volume 22, Issue 42, Page(s) 24624–24632

    Abstract: Neutral iron oxide clusters (FenOm, n, m ≤ 16) are produced in a laser vaporization source using O2 gas seeded in He. The neutral clusters are ionized with a sequence of femtosecond laser pulses and detected using time-of-flight mass spectrometry. Small ... ...

    Abstract Neutral iron oxide clusters (FenOm, n, m ≤ 16) are produced in a laser vaporization source using O2 gas seeded in He. The neutral clusters are ionized with a sequence of femtosecond laser pulses and detected using time-of-flight mass spectrometry. Small clusters are confirmed to be most prominent in the stoichiometric (n = m) distribution, with m = n + 1 clusters observed above n = 4. Pump-probe spectroscopy is employed to study the dynamics of an electron transfer from an oxygen orbital to an iron nonbonding orbital of iron oxide clusters that is driven by absorption of a 400 nm photon. A bifurcation of the initial wavepacket occurs, where a femtosecond component is attributed to electron relaxation assisted through internuclear vibrational relaxation and high density of states, and a slow relaxation shows the formation of a bound excited state. The lifetime and relative ratio of the two pathways depend on both the cluster size and iron oxidation state. The femtosecond lifetime decreases with increased cluster size until a saturation timescale is achieved at n > 5. The relative population of the long-lived excited state decreases with cluster size and suggests that the excited electron remains on the Fe atom for >20 ps.
    Language English
    Publishing date 2020-10-23
    Publishing country England
    Document type Journal Article
    ZDB-ID 1476244-4
    ISSN 1463-9084 ; 1463-9076
    ISSN (online) 1463-9084
    ISSN 1463-9076
    DOI 10.1039/d0cp03889j
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  9. Article ; Online: Oscillation in Excited State Lifetimes with Size of Sub-nanometer Neutral (TiO

    Garcia, Jacob M / Heald, Lauren F / Shaffer, Ryan E / Sayres, Scott G

    The journal of physical chemistry letters

    2021  Volume 12, Issue 16, Page(s) 4098–4103

    Abstract: Neutral titanium oxide clusters of up to 1 nm in diameter ( ... ...

    Abstract Neutral titanium oxide clusters of up to 1 nm in diameter (TiO
    Language English
    Publishing date 2021-04-22
    Publishing country United States
    Document type Journal Article
    ISSN 1948-7185
    ISSN (online) 1948-7185
    DOI 10.1021/acs.jpclett.1c00840
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  10. Article ; Online: Effect of oxidation on excited state dynamics of neutral Ti

    Garcia, Jacob M / Heald, Lauren F / Shaffer, Ryan E / Sayres, Scott G

    The Journal of chemical physics

    2021  Volume 155, Issue 21, Page(s) 211102

    Abstract: Excited state lifetimes of neutral titanium oxide clusters ( ... ...

    Abstract Excited state lifetimes of neutral titanium oxide clusters (Ti
    Language English
    Publishing date 2021-12-08
    Publishing country United States
    Document type Journal Article
    ZDB-ID 3113-6
    ISSN 1089-7690 ; 0021-9606
    ISSN (online) 1089-7690
    ISSN 0021-9606
    DOI 10.1063/5.0071264
    Database MEDical Literature Analysis and Retrieval System OnLINE

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