Imaging temperature and thickness of thin planar liquid water jets in vacuum.

We present spatially resolved measurements of the temperature of a flat liquid water microjet for varying ambient pressures, from vacuum to 100% relative humidity. The entire jet surface is probed in a single shot by a high-resolution infrared camera. Obtained 2D images are substantially influenced by the temperature of the apparatus on the opposite side of the infrared camera; a protocol to correct for the thermal background radiation is presented.

Photoelectron spectroscopy from a liquid flatjet.

We demonstrate liquid-jet photoelectron spectroscopy from a flatjet formed by the impingement of two micron-sized cylindrical jets of different aqueous solutions. Flatjets provide flexible experimental templates enabling unique liquid-phase experiments that would not be possible using single cylindrical liquid jets. One such possibility is to generate two co-flowing liquid-jet sheets with a common interface in vacuum, with each surface facing the vacuum being representative of one of the solutions, allowing face-sensitive detection by photoelectron spectroscopy.

Imaging of Chemical Kinetics at the Water-Water Interface in a Free-Flowing Liquid Flat-Jet.

We present chemical kinetics measurements of the luminol oxidation chemiluminescence (CL) reaction at the interface between two aqueous solutions, using liquid jet technology. Free-flowing liquid microjets are a relatively recent development that have found their way into a growing number of applications in spectroscopy and dynamics. A variant thereof, called flat-jet, is obtained when two cylindrical jets of a liquid are crossed, leading to a chain of planar leaf-shaped structures of the flowing liquid.

A setup for studies of photoelectron circular dichroism from chiral molecules in aqueous solution.

We present a unique experimental design that enables the measurement of photoelectron circular dichroism (PECD) from chiral molecules in aqueous solution. The effect is revealed from the intensity difference of photoelectron emission into a backward-scattering angle relative to the photon propagation direction when ionizing with circularly polarized light of different helicity. This leads to asymmetries (normalized intensity differences) that depend on the handedness of the chiral sample and exceed the ones in conventional dichroic mechanisms by orders of magnitude.

A new Stark decelerator based surface scattering instrument for studying energy transfer at the gas-surface interface.

We report on the design and characterization of a new apparatus for performing quantum-state resolved surface scattering experiments. The apparatus combines optical state-specific molecule preparation with a compact hexapole and a Stark decelerator to prepare carrier gas-free pulses of quantum-state pure CO molecules with velocities controllable between 33 and 1000 m/s with extremely narrow velocity distributions. The ultrahigh vacuum surface scattering chamber includes homebuilt ion and electron detectors, a closed-cycle helium cooled single crystal sample mount capable of tuning surface temperature between 19 and 1337 K, a Kelvin probe for non-destructive work function measurements, a precision leak valve manifold for targeted adsorbate deposition, an inexpensive quadrupole mass spectrometer modified to perform high resolution temperature programmed desorption experiments and facilities to clean and characterize the surface.

Vibrational enhancement of electron emission in CO (a3Π) quenching at a clean metal surface.

We have combined a Stark decelerator with a molecular beam-surface scattering setup to accurately measure the absolute electron emission yield, γ, of CO (a(3)Π) quenching at a Au(111) surface with quantum state resolution. We clearly observe an enhanced probability of electron emission when scattering vibrationally excited states of CO from the surface.

A compact hexapole state-selector for NO radicals.

Focusing of molecular beams using an electrostatic hexapole is a mature technique to produce samples of state-selected molecules. The ability to efficiently focus molecules depends on the properties of the molecular species of interest, the length of the hexapole state selector, as well as on the maximum electric field strength that can be achieved in these devices. In particular for species with a small effective dipole moment such as nitric oxide (NO), hexapole state selectors of several meters in length are required to focus the beam.

A traveling wave decelerator for neutral polar molecules.

Recently, a decelerator for neutral polar molecules has been presented that operates on the basis of macroscopic, three-dimensional, traveling electrostatic traps [A. Osterwalder, S. A.

An electrostatic elliptical mirror for neutral polar molecules.

Focusing optics for neutral molecules finds application in shaping and steering molecular beams. Here we present an electrostatic elliptical mirror for polar molecules consisting of an array of microstructured gold electrodes deposited on a glass substrate. Alternating positive and negative voltages applied to the electrodes create a repulsive potential for molecules in low-field-seeking states.

Rotational-state-specific guiding of large molecules.

A beam of polar molecules can be focused and transported through an ac electric quadrupole guide. At a given ac frequency, the transmission of the guide depends on the mass-to-dipole-moment (m/μ) ratio of the molecular quantum state. Here we present a detailed characterization of the m/μ selector, using a pulsed beam of benzonitrile (C(6)H(5)CN) molecules in combination with rotational quantum state resolved detection.

A linear AC trap for polar molecules in their ground state.

A linear AC trap for polar molecules in high-field seeking states has been devised and implemented, and its characteristics have been investigated both experimentally and theoretically. The trap is loaded with slow 15ND3 molecules in their ground state (para-ammonia) from a Stark decelerator. The trap's geometry offers optimal access as well as improved loading.