scholarly journals Communication: Effect of Oxidation on Excited State Dynamics of Neutral TinO2n-x (n<10, x<4) Clusters

2021 ◽  
Author(s):  
Jacob Garcia ◽  
Lauren Heald ◽  
Ryan Shaffer ◽  
Scott Sayres
Keyword(s):  
Excited State ◽  
Closed Shell ◽  
Laser Pulses ◽  
Fast Response ◽  
Relaxation Mechanism ◽  
Femtosecond Laser Pulses ◽  
Charge Carriers ◽  
Electronic Relaxation ◽  
Excited State Lifetime ◽  
Localization Of Charge Carriers

Excited state lifetimes of neutral titanium oxide clusters (TinO2n-x, n < 10, x < 4) were measured using a sequence of 400 nm pump and 800 nm probe femtosecond laser pulses. Despite large differences in electronic properties between the closed shell stoichiometric TinO2n clusters and the suboxide TinO2n-x (x = 1-3) clusters, the transient responses for all clusters contain a fast response of 35 fs followed by a sub-picosecond excited state lifetime. In this non-scalable size regime, subtle changes in the sub-ps lifetimes are attributed to variations in the coordination of Ti atoms and localization of charge carriers following UV photoexcitation. In general, clusters exhibit longer lifetimes with increased size and also with addition of O atoms. This suggests that removal of O atoms develops stronger Ti-Ti interactions as the system transitions from a semiconducting character into a fast metallic electronic relaxation mechanism.

scholarly journals Nonperturbative generation of above-threshold harmonics from pre-excited argon atoms in intense mid-infrared laser fields

2017 ◽  
Vol 5 ◽  
Author(s):  
Guihua Li ◽  
Hongqiang Xie ◽  
Ziting Li ◽  
Jinping Yao ◽  
Wei Chu ◽  
...  
Keyword(s):  
Excited State ◽  
Femtosecond Laser ◽  
Pulse Energy ◽  
Laser Pulses ◽  
Infrared Laser ◽  
Femtosecond Laser Pulses ◽  
Probe Laser ◽  
Laser Fields ◽  
Mid Infrared ◽  
Highly Nonlinear

We experimentally investigate the generation of above-threshold harmonics completely from argon atoms on an excited state using mid-infrared femtosecond laser pulses. The highly nonlinear dependences of the observed signal on the pulse energy and polarization of the probe laser pulses indicate its nonperturbative characteristic.

Investigating the role of human serum albumin protein pocket on the excited state dynamics of indocyanine green using shaped femtosecond laser pulses

2015 ◽  
Vol 17 (8) ◽  
pp. 5872-5877 ◽  
Author(s):  
Muath Nairat ◽  
Arkaprabha Konar ◽  
Marie Kaniecki ◽  
Vadim V. Lozovoy ◽  
Marcos Dantus
Keyword(s):  
Excited State ◽  
Human Serum Albumin ◽  
Serum Albumin ◽  
Indocyanine Green ◽  
Human Serum ◽  
Laser Pulses ◽  
Femtosecond Laser Pulses ◽  
Vibrational Motion ◽  
Protein Pocket

When indocyanine green (ICG) is confined inside the pocket of human serum albumin its triplet state formation is mitigated and coherent vibrational motion becomes more observable.

scholarly journals Oscillation in Excited State Lifetimes with Size of Sub-Nanometer Neutral (TiO2)n Clusters Observed with Ultrafast Pump-Probe Spectroscopy

2021 ◽  
Author(s):  
Jacob Garcia ◽  
Lauren Heald ◽  
ryan shaffer ◽  
Scott Sayres
Keyword(s):  
Excited State ◽  
Density Functional ◽  
Density Functional Theory Calculations ◽  
Laser Pulses ◽  
Femtosecond Laser Pulses ◽  
Laser Vaporization ◽  
Carrier Recombination ◽  
Electron Hole Pair ◽  
Excited State Lifetimes ◽  
Probe Spectroscopy

<div>Neutral titanium oxide clusters of up to 1 nm in diameter (TiO<sub>2</sub>)<sub>n</sub>, with n < 10, are produced in a laser vaporization source and subsequently ionized by a sequence of femtosecond laser pulses. Using 400 nm pump, 800 nm probe lasers, the excited state lifetimes of neutral (TiO<sub>2</sub>)<sub>n</sub> clusters are measured. All clusters exhibit a rapid relaxation lifetime of ~30 fs, followed by a sub-picosecond lifetime that we attribute to carrier recombination. The excited state lifetimes oscillate with size, with even numbered clusters possessing longer lifetimes. Density functional theory calculations show the excited state lifetimes are correlated with electron-hole pair localization or polaron-like formation in the excited states of neutral clusters. Thus, structural rigidity is suggested as a feature for extending excited state lifetimes in titania materials.</div>

scholarly journals Ultrafast Pump-Probe Spectroscopy of Finite-Sized Neutral Iron Oxide Clusters

2020 ◽  
Author(s):  
Jacob Garcia ◽  
ryan shaffer ◽  
Scott Sayres
Keyword(s):  
Excited State ◽  
Iron Oxide ◽  
Cluster Size ◽  
Iron Oxidation ◽  
Laser Pulses ◽  
Femtosecond Laser Pulses ◽  
Laser Vaporization ◽  
Relative Population ◽  
Pump Probe ◽  
Probe Spectroscopy

<div><p>Neutral iron oxide clusters (Fe<sub>n</sub>O<sub>m</sub>, n,m ≤ 16) are produced in a laser vaporization source using O<sub>2</sub>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 prominant 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 a slow relaxation shows the formation of a bound excited state. The lifetime and relative ratio of the two pathways depends 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. </p></div>

scholarly journals Ultrafast Pump-Probe Spectroscopy of Finite-Sized Neutral Iron Oxide Clusters

2020 ◽  
Author(s):  
Jacob Garcia ◽  
ryan shaffer ◽  
Scott Sayres
Keyword(s):  
Excited State ◽  
Iron Oxide ◽  
Cluster Size ◽  
Iron Oxidation ◽  
Laser Pulses ◽  
Femtosecond Laser Pulses ◽  
Laser Vaporization ◽  
Relative Population ◽  
Pump Probe ◽  
Probe Spectroscopy

<div><p>Neutral iron oxide clusters (Fe<sub>n</sub>O<sub>m</sub>, n,m ≤ 16) are produced in a laser vaporization source using O<sub>2</sub>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 prominant 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 a slow relaxation shows the formation of a bound excited state. The lifetime and relative ratio of the two pathways depends 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. </p></div>

scholarly journals Oscillation in Excited State Lifetimes with Size of Sub-Nanometer Neutral (TiO2)n Clusters Observed with Ultrafast Pump-Probe Spectroscopy

2021 ◽  
Author(s):  
Jacob Garcia ◽  
Lauren Heald ◽  
ryan shaffer ◽  
Scott Sayres
Keyword(s):  
Excited State ◽  
Density Functional ◽  
Density Functional Theory Calculations ◽  
Laser Pulses ◽  
Femtosecond Laser Pulses ◽  
Laser Vaporization ◽  
Carrier Recombination ◽  
Electron Hole Pair ◽  
Excited State Lifetimes ◽  
Probe Spectroscopy

<div>Neutral titanium oxide clusters of up to 1 nm in diameter (TiO<sub>2</sub>)<sub>n</sub>, with n < 10, are produced in a laser vaporization source and subsequently ionized by a sequence of femtosecond laser pulses. Using 400 nm pump, 800 nm probe lasers, the excited state lifetimes of neutral (TiO<sub>2</sub>)<sub>n</sub> clusters are measured. All clusters exhibit a rapid relaxation lifetime of ~30 fs, followed by a sub-picosecond lifetime that we attribute to carrier recombination. The excited state lifetimes oscillate with size, with even numbered clusters possessing longer lifetimes. Density functional theory calculations show the excited state lifetimes are correlated with electron-hole pair localization or polaron-like formation in the excited states of neutral clusters. Thus, structural rigidity is suggested as a feature for extending excited state lifetimes in titania materials.</div>

scholarly journals Достижение субпикосекундного временного разрешения при исследовании процессов анизотропной релаксации биологических молекул

2020 ◽  
Vol 46 (4) ◽  
pp. 7
Author(s):  
И.А. Горбунова ◽  
М.Э. Сасин ◽  
О.С. Васютинский
Keyword(s):  
Energy Transfer ◽  
Excited State ◽  
Excited States ◽  
Rotational Diffusion ◽  
Laser Pulses ◽  
Femtosecond Laser Pulses ◽  
Polyatomic Molecules ◽  
Biological Molecules ◽  
Pump Probe ◽  
First Time

A novel pump-probe method has been developed to study anisotropic relaxation and energy transfer in excited states of polyatomic molecules excited by femtosecond laser pulses. The method was used to study the rotational diffusion of NADH with a temporal resolution of about 0.6 ps. For the first time, absorption from the excited state of biological molecules pumped by laser pulses with energies of 1 nJ was detected

Inorganic-organic Hybrid Materials for Real 3-D Sub-νm Lithography

2003 ◽  
Vol 780 ◽  
Author(s):  
R. Houbertz ◽  
J. Schulz ◽  
L. Fröhlich ◽  
G. Domann ◽  
M. Popall ◽  
...  
Keyword(s):  
Femtosecond Laser ◽  
Sol Gel ◽  
Laser Pulses ◽  
Femtosecond Laser Pulses ◽  
Hybrid Polymer ◽  
Organic Hybrid ◽  
Two Photon ◽  
Applied Technology ◽  
Scale Structures ◽  
Sol Gel Synthesis

AbstractReal 3-D sub-νm lithography was performed with two-photon polymerization (2PP) using inorganic-organic hybrid polymer (ORMOCER®) resins. The hybrid polymers were synthesized by hydrolysis/polycondensation reactions (modified sol-gel synthesis) which allows one to tailor their material properties towards the respective applications, i.e., dielectrics, optics or passivation. Due to their photosensitive organic functionalities, ORMOCER®s can be patterned by conventional photo-lithography as well as by femtosecond laser pulses at 780 nm. This results in polymerized (solid) structures where the non-polymerized parts can be removed by conventional developers.ORMOCER® structures as small as 200 nm or even below were generated by 2PP of the resins using femtosecond laser pulses. It is demonstrated that ORMOCER®s have the potential to be used in components or devices built up by nm-scale structures such as, e.g., photonic crystals. Aspects of the materials in conjunction to the applied technology are discussed.

Ablation of metals with femtosecond laser pulses

2001 ◽  
Author(s):  
K. H. Leong ◽  
T. Y. Plew ◽  
R. L. Maynard ◽  
A. A. Said ◽  
L. A. Walker
Keyword(s):  
Femtosecond Laser ◽  
Laser Pulses ◽  
Femtosecond Laser Pulses
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