Nonlinear Optical Response and Ultrafast Dynamics in C₆₀

Abstract

Crossed molecular beams experiments were conducted to investigate the chemical dynamics of the reaction of dicarbon molecules, C(2)(X(1)Sigma(g)(+)/a(3)Pi(u)), with diacetylene, C(4)H(2)(X(1)Sigma(g)(+)) at two collision energies of 12.1 and 32.8 kJ mol(-1). The dynamics were found to be indirect, involved C(6)H(2) intermediates, and were dictated by an initial addition of the dicarbon molecule to the carbon-carbon triple bond of diacetylene. The initial collision complexes could isomerize. On the singlet surface, the resulting linear triacetylene molecule (C(6)H(2)(X(1)Sigma(g)(+))) decomposed without an exit barrier to form the linear 1,3,5-hexatriynyl radical (C(6)H(X(2)Pi)). On the triplet surface, the dynamics suggested at least a tight exit transition state involved in the fragmentation of a triplet C(6)H(2) intermediate to yield the 1,3,5-hexatriynyl radical (C(6)H(X(2)Pi)) plus atomic hydrogen. On the basis of the experimental data, we recommend an experimentally determined enthalpy of formation of the 1,3,5-hexatriynyl radical of 1014 +/- 27 kJ mol(-1) at 0 K. Our experimental results and the derived reaction mechanisms gain full support from electronic structure calculations on the singlet and triplet C(6)H(2) potential-energy surfaces. The identification of the 1,3,5-hexatriynyl radical under single collision conditions implies that the neutral-neutral reaction of dicarbon with diacetylene can lead to the formation of 1,3,5-hexatriynyl radicals in the interstellar medium and possibly in the hydrocarbon-rich atmospheres of planets and their moons such as Saturn's satellite Titan.

In situ nonlinear optical spectroscopy of electron–phonon couplings at alkali‐doped C60/Ag(111) interfaces

“…LUMO þ 1 transition [24,25]. This transition is also thought to be responsible of enhancement of other optical nonlinear processes [4]. At this stage, however, we cannot exclude electronic transitions originating from the t 1u -derived molecular orbitals, as this energy level is partially filled at the Fermi level due to the charge transfer occurring upon adsorption (from the metal substrate to the fullerene).…”

“…In particular, the characterization of the fullerene electron-phonon couplings is fundamental to understand superconductivity in the fullerides [1,2] or the Jahn-Teller distortion in C 60 anions [3], for example. The nonlinear optical response of fullerene molecules is also the subject of current, intensive research, with many questions still unanswered [4].…”

Biological activity of fullerenes - reality and prospects

“…Свойство молекул фуллеренов (как уже указы-валось выше) под действием видимого света пере-ходить в возбужденное состояние, превращая три-плетный кислород 3 O 2 в синглетный 1 O 2 , позволяет использовать их в фотодинамической терапии (ФДТ) в качестве фотосенситизаторов [8].…”

“…В частности, фулле-рены, склонность к агрегации которых высока за счет поверхностных липофильных атомов, способ-ны действовать на живые системы и как отдель-ные молекулы, и как нано частицы. Именно поэтому фуллерены назы вают символом нанонауки [3]. Так как все на ноструктуры углерода, за исключени-ем наноалмазов, построены из атомов углерода в sp 2 -гибридизации, то и некоторые свойства у них одинаковые, как, например, характерное проявле-ние фотодинамических свойств при освещении ви-димым светом [4].…”

First-principles prediction of optical second-order harmonic generation in the endohedralN@C60compound

“…Non-linear-optical response in pure C 60 and other endohedral fullerenes has already attracted a huge interest for over two decades [4][5][6]. Successful implantation of a nitrogen atom into C 60 [7] has opened a frontier for possible molecule-based quantum computing [8,9].…”