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Atomic sp, sp2, and sp3 hybrid orbitals were introduced by Linus Pauling to explain the nature of the chemical bond. Quantum dynamics simulations show that they can be sculpted by means of a selective series of coherent laser pulses, starting from the 1s orbital of the hydrogen atom. Laser hybridization generates atoms with state‐selective electric dipoles, opening up new possibilities for the study of chemical reaction dynamics and heterogeneous catalysis. 相似文献
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Inside Back Cover: On the Resolution Limit of Femtosecond Stimulated Raman Spectroscopy: Modelling Fifth‐Order Signals with Overlapping Pulses (ChemPhysChem 16/2015) 下载免费PDF全文
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《Angewandte Chemie (International ed. in English)》2017,56(20):5471-5474
We present a proof of concept that ultrafast dynamics combined with photochemical stability information of molecular photocatalysts can be acquired by electrospray ionization mass spectrometry combined with time‐resolved femtosecond laser spectroscopy in an ion trap. This pump‐probe “fragmentation action spectroscopy” gives straightforward access to information that usually requires high purity compounds and great experimental efforts. Results of gas‐phase studies on the electronic dynamics of two supramolecular photocatalysts compare well to previous findings in solution and give further evidence for a directed electron transfer, a key process for photocatalytic hydrogen generation. 相似文献
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Can a Six‐Letter Alphabet Increase the Likelihood of Photochemical Assault to the Genetic Code? 下载免费PDF全文
Brennan Ashwood Marvin Pollum Prof. Dr. Carlos E. Crespo‐Hernández 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(46):16648-16656
In 2014, two unnatural nucleosides, d5SICS and dNaM, were shown to selectively base pair and replicate with high fidelity in a modified strain of E. coli, thus effectively expanding its genetic alphabet from four to six letters. More recently, a significant reduction in cell proliferation was reported in cells cultured with d5SICS, and putatively with dNaM, upon exposure to brief periods of near‐visible radiation. The photosensitizing properties of the lowest‐energy excited triplet state of both d5SICS and dNaM were implicated in their cytotoxicity. Importantly, however, the excited‐state mechanisms by which near‐visible excitation populates the triplet states of d5SICS and dNaM are currently unknown. In this study, steady‐state and time‐resolved spectroscopies are combined with quantum‐chemical calculations in order to reveal the excited‐state relaxation mechanisms leading to efficient population of the triplet states in these unnatural nucleosides in solution. It is shown that excitation of d5SICS or dNaM with near‐visible light leads overwhelmingly to ultrafast population of their triplet states on the femtosecond time scale. The results presented in this work lend strong support to the proposal that photoexcitation of these unnatural nucleosides can accelerate oxidatively generated damage to DNA and other biomolecules within the cellular environment. 相似文献
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Hideyuki Tatsuno Kasper S. Kjr Kristjan Kunnus Tobias C. B. Harlang Cornelia Timm Meiyuan Guo Pavel Chbera Lisa A. Fredin Robert W. Hartsock Marco E. Reinhard Sergey Koroidov Lin Li Amy A. Cordones Olga Gordivska Om Prakash Yizhu Liu Mads G. Laursen Elisa Biasin Frederik B. Hansen Peter Vester Morten Christensen Kristoffer Haldrup Zoltn Nmeth Dorottya Srosin Szemes va Bajnczi Gyrgy Vank Tim B. Van Driel Roberto Alonso‐Mori James M. Glownia Silke Nelson Marcin Sikorski Henrik T. Lemke Dimosthenis Sokaras Sophie E. Canton Asmus O. Dohn Klaus B. Mller Martin M. Nielsen Kelly J. Gaffney Kenneth Wrnmark Villy Sundstrm Petter Persson Jens Uhlig 《Angewandte Chemie (International ed. in English)》2020,59(1):364-372
Iron N‐heterocyclic carbene (NHC) complexes have received a great deal of attention recently because of their growing potential as light sensitizers or photocatalysts. We present a sub‐ps X‐ray spectroscopy study of an FeIINHC complex that identifies and quantifies the states involved in the deactivation cascade after light absorption. Excited molecules relax back to the ground state along two pathways: After population of a hot 3MLCT state, from the initially excited 1MLCT state, 30 % of the molecules undergo ultrafast (150 fs) relaxation to the 3MC state, in competition with vibrational relaxation and cooling to the relaxed 3MLCT state. The relaxed 3MLCT state then decays much more slowly (7.6 ps) to the 3MC state. The 3MC state is rapidly (2.2 ps) deactivated to the ground state. The 5MC state is not involved in the deactivation pathway. The ultrafast partial deactivation of the 3MLCT state constitutes a loss channel from the point of view of photochemical efficiency and highlights the necessity to screen transition‐metal complexes for similar ultrafast decays to optimize photochemical performance. 相似文献
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飞秒物理、飞秒化学和飞秒生物学 总被引:7,自引:0,他引:7
飞秒激光技术因其极高的时间分辨特性而被广泛应用于研究多种材料的超快过程,文章从几个侧面就飞秒技术在物理学,化学及生物学等方面的应用作了介绍,在飞秒物理方面,介绍了飞秒技术在研究半导体量子阱材料,纳米材料的性质及高次谐波产生等方面的研究进展,飞秒化学则主要介绍了飞秒技术在研究光化学反应,光解离过程、键的断裂及结合以及相关的动力学过程的应用;在生物方面,则介绍利用飞秒技术研究光合作用中的能量传递过程,视觉系统中的光致异构化过程以及DNA中的电荷传递及质子传递等过程的研究现状。 相似文献
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