Direct observation of the ultrafast electron transfer process in a polymer/fullerene blend

Photoinduced electron transfer in organic molecules is a topic of fundamental interest in photophysics and for applications to artificial photosynthesis. The detailed time resolution of this process is needed to shed light on the charge transfer mechanism. We perform ultrafast experiments on conjugated polymer/C60 blends with sub-10-fs time resolution. We are able to time resolve for the first time the charge transfer process, obtaining a time constant ≈45 fs

Direct observation of the ultrafast electron transfer process in a polymer/fullerene blend

Photoinduced electron transfer in organic molecules is an extensively investigated topic both because of fundamental interest in the photophysics and for applications to artificial photosynthesis. Highly efficient ultrafast electron transfer from photoexcited conjugated polymers to C60 has been reported, the back transfer is heavily hindered, thus providing an intrinsic stabilization mechanism of the photogenerated charges. Although an upper limit for the forward electron transfer time of 1 ps has been reported, its detailed time resolution is still missing and is highly needed to shed light on the photophysics of the charge transfer mechanism. We perform ultrafast experiments on conjugated polymer/C60 blends with sub-10-fs time resolution. We are able to time resolve for the first time the charge transfer process, obtaining a forward electron transfer time constant τct≈45 fs

Luminescence and formation of alkali-halide ionic excimers in solid Ne and Ar

Transitions from ionic states A²⁺X– of alkalihalides CsF, CsCl and RbF isolated in solid Ne and Ar films recorded under pulsed e-beam excitation are studied. The B(²∑₁/₂)-X(²∑₁/₂) and C(²П₃/₂)-A(²П₃/₂) luminescence bands of Cs2+F– (196.5 nm, 227 nm), Cs²⁺Cl– (220.1 nm, 249.2 nm) and Rb²⁺F– (136 nm) in Ne, and a weakerB–X emission of Cs²⁺F– (211.2 nm) in Ar are identified. For CsF the depopulation of the A²⁺X– state is dominated by the radiative decay. A ratio of the recorded exciplex emission intensities of I(CsF)/I(CsCl)/I(RbF) = 20/5/1 reflects the luminescence efficiency and for RbF and CsCl a competitive emission channel due to predissociation in the A²⁺X⁻(B²∑₁/₂) state is observed. For these molecules an efficient formation of the state X*₂ is confirmed through recording the molecular D`(³П₂g)-A`(³П₂u) transition. A strong dependence of the luminescence intensities on the alkalihalide content reveals quenching at concentrations higher than 0.7%

Solid state excimer lasers

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