Perturbation-Assisted Laser-Induced Atomic Fragment Fluorescence Spectroscopy: A Facile Route to Spin-Forbidden States

Laser-induced atomic fragment fluorescence spectroscopy: A facile technique for molecular spectroscopy of spin-forbidden states

Spectra of spin-forbidden and spin-allowed transitions in the mixed b$^3Π_u$ ~ A$^1Σ_u^+$ state of Na$_2$ are measured separately by two-photon excitation using a single tunable dye laser. The two-photon excitation produces Na*(3p) by photodissociation, which is easily and sensitively detected by atomic fluorescence. At low laser power, only the A$^1Σ_u^+$ state is excited, completely free of triplet excitation. At high laser power, photodissociation via the b$^3Π_u$ triplet state intermediate becomes much more likely, effectively "switching" the observations from singlet spectroscopy to tripl…

Temperature Dependent Product Yields for the Spin Forbidden Singlet Channel of the C(3P) + C2H2 Reaction

The atomic hydrogen formation channels of the C + C2H2 reaction have been investigated using a continuous supersonic flow reactor over the 52 K 296 K temperature range. H-atoms were detected directly at 121.567 nm by vacuum ultraviolet laser induced fluorescence. Absolute H-atom yields were determined by comparison with the H-atom signal generated by the C + C2H4 reaction. The product yields agree with earlier crossed beam experiments employing universal detection methods. Incorporating these branching ratios in a gas-grain model of dense interstellar clouds increases the cC3H abundance. This …

Spectroscopy of Rb$_{2}$ dimers in solid $^{4}$He

We present experimental and theoretical studies of the absorption, emission and photodissociation spectra of Rb$_{2}$ molecules in solid helium. We have identified 11 absorption bands of Rb$_{2}$. All laser-excited molecular states are quenched by the interaction with the He matrix. The quenching results in efficient population of a metastable (1)$^{3}Π_{u}$ state, which emits fluorescence at 1042 nm. In order to explain the fluorescence at the forbidden transition and its time dependence we propose a new molecular exciplex Rb$_{2}(^{3}Π_{u})$He$_{2}$. We have also found evidence for the forma…

三重激子对中反称交换介导的自旋依赖荧光

Spin dependent fluorescence mediated by anti-symmetric exchange in triplet exciton pairs

本研究探讨了Dzyaloshinskii-Moriya相互作用（DMI）对三重激子对自旋依赖荧光的影响，揭示其通过诱导自旋流形能级交叉改变自旋布居和TTA速率，推进了对光电子学中自旋依赖现象的理解。

Determination of CaOH and CaOCH$_3$ vibrational branching ratios for direct laser cooling and trapping

Alkaline earth monoalkoxide free radicals (MORs) have molecular properties conducive to direct laser cooling to sub-millikelvin temperatures. Using dispersed laser induced fluorescence (DLIF) measurements from a pulsed supersonic molecular beam source we determine vibrational branching ratios and Franck-Condon factors for the MORs CaOH and CaOCH$_{3}$. With narrow linewidth continuous-wave dye laser excitation, we precisely measure fluorescence branching for both $\tilde{X}-\tilde{A}$ and $\tilde{X}-\tilde{B}$ electronic systems in each molecule. Weak symmetry-forbidden decays to excited bendi…

Triplet-Polaron Interaction Induced Upconversion from Triplet to Singlet: a New Way to Obtain Highly Efficient OLEDs

The triplet harvesting is a main challenge in organic light-emitting devices (OLEDs), due to the radiative decay of triplet is spin-forbidden. Here, we designed and synthesized two D-A type molecules, TPA-TAZ and TCP. The OLEDs based on them exhibit deep-blue emission and the singlet formation ratios are higher than the simple spin-statistics of 25 %. Specially, a TPA-TAZ-based OLED achieves a maximum EQE of 6.8 %, which is the largest value of the undoped OLEDs with CIE(y)< 0.06 (the EBU blue standard) up to date. Comprehensive experiments eliminate the triplet-harvesting processes of thermal…