Ultrafast pump–probe spectroscopy of neutral Fe n O m clusters ( n , m &lt; 16)

Phys. Chem. Chem. Phys.

Sayres

2022

Self Cite

Section: Experimental Methodsmentioning

confidence: 99%

Section: Experimental Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Orbital-dependent photodynamics of strongly correlated nickel oxide clusters

Phys. Chem. Chem. Phys.

Sayres

2022

Self Cite

“…The experimental methods and instrumental setup were described previously. 26,27 Briefly, neutral clusters were produced through ablation of a pure 0.25" diameter Ti rod by the second harmonic of a pulsed Nd:YAG laser in the presence of a seeded He gas pulse (1% O2). The ablation plume was confined to a 1 x 60 mm collision region and reduced to a molecular beam diameter of 2 mm by a charged skimmer, deflecting all but the neutral clusters.…”

Section: Experimental Methodsmentioning

confidence: 99%

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

Heald

shaffer

et al. 2021

Preprint

Self Cite

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.

“…Here, we report the excited state transient signals of neutral Cr2On (n = 0-4) clusters using two-color pump-probe spectroscopy and apply theoretical calculations to understand the increasing metallic behavior as a function of sequential oxidation. A time-of-flight mass spectrometer (TOF-MS) 20,21 coupled to synchronized sub-35 fs laser pulses was employed to measure the excited state lifetimes of neutral Cr oxide clusters. A single 400 nm (3.1 eV) pump photon initiates a charge transfer and relaxation mechanism that is probed through ionization by a synchronized strong-field 800 nm (1.55 eV) probe beam.…”

mentioning

confidence: 99%

Increased Excited State Metallicity in Neutral Cr2On Clusters (n < 5) Upon Sequential Oxidation

Sayres

2021

Preprint

Self Cite

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 sub-picosecond 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.