A simple method to control molecular translation with a chemical reaction is demonstrated. Slow NO molecules have been produced by partially canceling the molecular beam velocity of NO$_2$ with the recoil velocity of the NO photofragment. The NO$_2$ molecules were photodissociated using a UV laser pulse polarized parallel to the molecular beam. The spatial profiles of NO molecules showed two peaks corresponding to decelerated and accelerated molecules, in agreement with theoretical prediction. A significant portion of the decelerated NO molecules stayed around the initial dissociation positions even several hundred nanoseconds after their production.
Quantum interference between multiple pathways in molecular photodissociation often results in angular momentum polarization of atomic products and this can give deep insight into fundamental physical processes. For dissociation of diatomic molecules the resulting orbital polarization is fully understood and consistent with quantum mechanical theory. For polyatomic molecules, however, coherent photofragment orbital polarization is frequently observed but so far has eluded theoretical explanation, and physical insight is lacking. Here we present a model of these effects for ozone photodissociat…
We propose a strategy for enabling photodissociation of a normally photostable molecule through coupling to a nanoparticle plasmon. The large possible coupling on the single-molecule level combined with the highly lossy nature of plasmonic modes, with lifetimes on the order of femtoseconds, opens an ultrafast decay channel for the molecule. For plasmon mode frequencies below the vertical photoexcitation energy of the molecule, the difference between excitation and emission energy is converted into vibrational energy on the molecular ground state in a Raman-like process. Under the correct condi…
Pure, highly nuclear-spin-polarized molecules have only been produced with molecular beam-separation methods, with production rates up to ${\sim}3{\times}10^{12}$ s$^{-1}$. Here, we propose the production of spin-polarized molecular photofragments from the IR-excitation and photodissociation of molecular beams, with production rates approaching the tabletop-IR-laser photon fluxes of $10^{21}$ s$^{-1}$. We give details on the production of spin-polarized molecular hydrogen and water isotopes, from formaldehyde and formic acid beams, respectively. Macroscopic quantities of these molecules are im…
Photodissociation spectroscopy of the dysprosium monochloride molecular ion
我们对分子离子DyCl $^+$的光解离截面进行了实验和理论研究。使用集成离子阱和飞行时间质谱仪测量光子能量范围为35，500 cm $^{-1}$至47，500 cm $^{-1}$的光解离截面;我们观察到在43，000 cm $^{-1}$附近达到峰值的宽的不对称轮廓。理论截面由电子势和跃迁偶极矩确定，电子势和跃迁偶极矩采用相对论组态相互作用、价键和耦合簇方法计算。DyCl $^+$的电子结构极其复杂，因为存在多个开放电子壳层，包括4f $^{10}$构型。该分子具有9个与离子键合的电子的吸引势和99个解离成基态Dy $^+$离子和Cl原子的排斥势。我们解释了缺乏对称性的横截面，由于从一个电子占主导地位的振动基态和几个解决排斥激发态之间的过渡的多个贡献。
We present a time-resolved study of the photodissociation dynamics of OCS after UV-photoexcitation at $λ=237$ nm. OCS molecules ($X\,^1Σ^+$) were primarily excited to the $1\,^1\!A''$ and the $2\,^1\!A'$ Renner-Teller components of the $^1Σ^{-}$ and $^1\!Δ$ states. Dissociation into CO and S fragments was observed through time-delayed strong-field ionisation and imaging of the kinetic energy of the resulting CO$^+$ and S$^+$ fragments by intense $790$ nm laser pulses. Surprisingly, fast oscillations with a period of $\sim100$ fs were observed in the S$^+$ channel of the UV dissociation. Based …
Probing the UV-Induced Photodissociation of CH$_\text{3}$I and C$_\text{6}$H$_\text{3}$F$_\text{2}$I with Femtosecond Time-Resolved Coulomb Explosion Imaging at FLASH
Slow, Continuous Beams of Large Gas Phase Molecules
冷，连续，高通量束的苯甲腈，氟苯，和苯甲醚已经创建。用低温气体的缓冲气体冷却提供了冷却和缓慢的向前射束速度。苯甲腈束被测量为具有峰值为67 $\pm 5$ m s $^{-1}$的前向速度，以及$10^{15}$分子s $^{-1}$的连续通量。这些光束为高分辨率光谱学提供了一个连续的光源，并为进一步空间操纵这些分子提供了一个有吸引力的起点，包括最终的捕获。
Continuous guided beams of slow and internally cold polar molecules
我们描述了缓冲气体冷却与静电速度过滤相结合，产生一个高通量的连续引导光束的内部冷和缓慢的极性分子。在以前的论文（L.D. van Buuren等人，arXiv：0806.2523v1），我们使用优化的设置呈现了关于氨和甲醛的引导光束的密度和状态纯度的结果。在这里，我们更详细地描述了低温源的技术方面、其操作以及我们为获得最佳性能而进行的优化实验。该源的多功能性通过生产不同分子种类的引导光束来证明。
We describe an apparatus to study the fragmentation of ion-molecule clusters triggered by laser excitation and transfer of an electron from the iodide to the neutral molecule. The apparatus comprises a source to generate ion-molecule clusters, a time-of-flight (TOF) spectrometer and a mass filter to select the desired anions, and a linear-plus-quadratic reflectron mass spectrometer to discriminate the fragment anions after the femtosecond laser excites the clusters. The fragment neutrals and anions are then captured by two channeltron detectors. The apparatus performance is tested by measuring…
Nitric oxide (NO) molecules initially traveling at 795 m/s in pulsed supersonic beams have been photoexcited to long-lived hydrogenic Rydberg-Stark states, decelerated and electrostatically trapped in a cryogenically cooled, chip-based transmission-line Rydberg-Stark decelerator. The decelerated and trapped molecules were detected $in$ $situ$ by pulsed electric field ionization. The operation of the decelerator was validated by comparison of the experimental data with the results of numerical calculations of particle trajectories. Studies of the decay of the trapped molecules on timescales up …
Electronic instabilities in transition metal compounds often spontaneously form orbital molecules, which consist of orbital-coupled metal ions at low temperature. Recent local structural studies utilizing the pair distribution function revealed that preformed orbital molecules appear disordered even in the high-temperature paramagnetic phase. However, it is unclear whether preformed orbital molecules are dynamic or static. Here, we provide clear experimental evidence of the slow dynamics of disordered orbital molecules realized in the high-temperature paramagnetic phase of LiVS2, which exhibit…
