All-optical nanoscopic spatial control of molecular reaction yields on nanoparticles

Abstract

Molecular adsorbate reactions on nanoparticles play a fundamental role in areas such as nano-photocatalysis, atmospheric, and astrochemistry. They can be induced, enhanced, and controlled by field localization and enhancement on the nanoparticle surface. In particular, the ability to perform highly controlled near-field-mediated reactions is key to deepening our understanding of surface photoactivity on nanosystems. Here, using reaction nanoscopy, we experimentally demonstrate all-optical nanoscopic control of surface reaction yields by tailoring the near fields on nanoparticles with waveform-controlled linear and bicircular two-color laser pulses, respectively. We observe site-selective proton emission from the dissociative ionization of adsorbate molecules on Si O 2 nanoparticles as a function of the polarization and relative phase of the two-color pulses. The angularly resolved close-to-uniform mapping between the surface reaction yields and the measured ion momentum enables the observation and spatial control of molecular reactions on the nanoparticle surface with nanoscopic resolution. The experimental results are modeled and reproduced qualitatively by classical trajectory Monte Carlo simulations. Our work paves the way toward reliable all-optical control of photocatalytic chemical reactions on nanoscale surfaces.

Strong field ionization of molecules on the surface of nanosystems

“…[20] The polarization and relative phase of the two-color laser fields significantly influence selective proton emission during dissociative ionization of molecules absorbed onto SiO 2 nanoparticles. [22]…”

“…[24,31] Similarly, the variation in the enhanced near field can be achieved either by changing the nanoparticle geometries or by tuning the incident laser waveforms, which can be reflected in the ionization of surface molecules. [15,22,33] When the incident laser intensity increases to approximately 10 14 W•cm −2 , the ionization processes can go into a different regime. In these cases, the generation of large amounts of free electrons and ions can induce dramatic interactions in nanoplasma.…”

Rydberg state excitation in molecules manipulated by bicircular two-color laser pulses

“…The BCTC laser fields have attracted considerable attention in steering two-dimensional directional bond breaking, 33 manipulating the electron-ion rescattering 34 and nonsequential double ionization (NSDI), [35][36][37][38] generating circularly polarized extreme ultraviolet light, [39][40][41] and spatially controlling surface reactions on nanoparticles at the nanoscale. 42 Past studies using BCTC laser fields mostly focused on the atomic and molecular ionization dynamics. [33][34][35][36][37][38][39][40][41][42] Until recently, the excitation dynamics of atoms and molecules via frustrated tunneling ionization 21 were theoretically studied with BCTC laser pulses, which, however, only takes into account the field effect.…”

“…The BCTC laser fields have attracted considerable attention in steering two-dimensional directional bond breaking, 33 manipulating the electron-ion rescattering 34 and nonsequential double ionization (NSDI), 35 – 38 generating circularly polarized extreme ultraviolet light, 39 – 41 and spatially controlling surface reactions on nanoparticles at the nanoscale 42 . Past studies using BCTC laser fields mostly focused on the atomic and molecular ionization dynamics 33 …”

“…Past studies using BCTC laser fields mostly focused on the atomic and molecular ionization dynamics 33 – 42 Until recently, the excitation dynamics of atoms and molecules via frustrated tunneling ionization 21 were theoretically studied with BCTC laser pulses, which, however, only takes into account the field effect 43 , 44 . In this article, we use these versatile BCTC laser fields to experimentally investigate the strong-field RSE of H2 molecules, where the created Rydberg fragments are measured and identified in the coincidence measurements.…”