Excimer

About: Excimer is a research topic. Over the lifetime, 3725 publications have been published within this topic receiving 75104 citations.

Modeling and diagnostics of silicon nitride deposition from 254‐nm Hg photosensitization of SiH4‐NH3 mixtures: Luminescence of HgNH3 excimer and laser‐induced fluorescence of NH2(Ã 2A1)

Abstract: Silicon nitride thin films are obtained from the Hg(63P1) ‐photosensitized decomposition of SiH4 and NH3 using the 254‐nm radiation of a low‐pressure Hg discharge lamp. Several diagnostics are associated to characterize the physicochemical mechanisms and measure the densities of reactive species or reaction products. The photon flux is obtained by radiometry, the Hg density is determined by absorption of the 254‐nm radiation, and the SiH4 gas depletion is measured by mass spectrometry. The luminescence at 340 nm of HgNH3 excimers is used as a probe of the metastable Hg(63P0) density and the NH2 radical is detected by laser‐induced fluorescence (LIF) using the 597.8‐nm line to excite NH2(A2A1) Σ(0,9,0) vibronic states.The interpretation of LIF results in terms of NH2 density takes into account collisional transfer and quenching of NH2(A2A1) revealed by nonexponential time decay of the fluorescence. In addition, the silicon nitride film deposition rate is monitored and the N/Si stoichiometry is determined...

Observation of exciplex emission from the mixed dimer of naphthalene and 2-methoxynaphthalene: A laser-induced fluorescence study in supersonic jet

Abstract: Exciplex formation in the van der Waals mixed dimer of naphthalene and 2-methoxynaphthalene has been investigated by using laser-induced fluorescence spectroscopy in supersonic jet. In contrast to the barrierless excimer formation in the S1 state of naphthalene homodimer, the exciplex formation in the mixed dimer occurs with a vibrational energy barrier of 466 cm−1. The energy gap between the S1 states of two molecules in the mixed dimer is 1000 cm−1. Therefore, the contribution of the exciton resonance interaction to the stability of the exciplex state is considered to be insignificant. Charge transfer interaction and the mixing of the charge transfer state with the locally excited state due to orbital overlap between two molecules at suitable geometry are proposed to be the decisive factors in formation of the exciplex.

Photophysical Processes in Polymers. VI. Spectroscopic Properties of 1‐Vinylpyrene and Poly(1‐Vinylpyrene)

Abstract: The absorption spectra, corrected fluorescence spectra, and fluorescence quantum yields of 1‐vinylpyrene and poly(1‐vinylpyrene) are reported. The triplet‐triplet absorption spectrum of poly(1‐vinylpyrene) is compared to that of pyrene, and the excimer fluorescence of the polymer is studied as a function of temperature. Based upon the temperature dependence of the excimer emission, it is concluded that efficient formation and inefficient emission of nonequilibrium‐geometry pyrene excimers takes place in poly(1‐vinylpyrene). Radiative and radiationless transition mechanisms are discussed. Values reported for poly(1‐vinylpyrene) in fluid solution at room temperature are qFM ≅ 0, qFD = 0.44, qPM ≅ 0, φT = 0.005, kFD = 0.83 × 107sec−1, kGD = 1.0 × 107sec−1, kDM >∼ 1 × 107sec−1, and kTM <∼ 5 × 105sec−1.