Gas Cluster Ion Beam-Assisted Deposition for Fabricating Dry Multilayers Containing Enzyme and Substrate with On-Demand Release.

Gas cluster ion beam (GCIB)-assisted deposition is used to build multilayered protein-based structures. In this process, Ar clusters bombard and sputter molecules from a reservoir (target) to a collector, an operation that can be sequentially repeated with multiple targets. The process occurs under a vacuum, making it adequate for further sample conservation in the dry state, since many proteins do not have long-term storage stability in the aqueous state.

Assignment of the methanol OH-stretch overtone spectrum using the pattern recognition method.

We present the measurement and analysis of the 2OH stretching band of methanol between 7165 cm and 7230 cm cooled down to 26 ± 12 K in a buffer gas cooling experiment. Measurements were performed with a cavity ring-down spectrometer having a detection limit = 2 × 10 cm. A total of 350 rovibrational transitions were assigned and 62 rovibrational transitions were tentatively assigned.

Enhancing Ion Signals and Improving Matrix Selection in Time-of-Flight Secondary Ion Mass Spectrometry with Microvolume Expansion Using Large Argon Clusters.

The molecular environment has an important impact on the ionization mechanism in time-of-flight secondary ion mass spectrometry (ToF-SIMS). In complex samples, desorption/ionization, and thus the detection of a molecular signal, can be hampered by molecular entanglement, ionization-suppressive neighbors, or even an unfavorable sample substrate. Here, a method called microvolume expansion is developed to overcome these negative effects.

Understanding the high-resolution spectral signature of the N2-H2O van der Waals complex in the 2OH stretch region.

We present the observation of the N2-H2O van der Waals complex in the 2OH stretch overtone region. The high-resolution jet cooled spectra were measured using a sensitive continuous wave cavity ringdown spectrometer. Several bands were observed and vibrationally assigned in terms of ν1, ν2, and ν3, the vibrational quantum numbers of the isolated H2O molecule, as (ν1'ν2'ν3')←(ν1″ν2″ν3″)=(200)←(000) and (101) ← (000).

Infrared Spectra of the Water-CO Complex in the 4.3-3.6 μm Region and Determination of the Ground State Tunneling Splitting for HDO-CO.

Spectra of water─CO dimers are studied using a tunable mid-infrared source to probe a pulsed slit jet supersonic expansion. HO-CO and DO-CO are observed in the CO ν fundamental region (≈2350 cm), DO-CO is also observed in the DO ν fundamental region (≈2790 cm), and HDO-CO is observed in the HDO O-D stretch fundamental region (≈2720 cm), all for the first time in these regions. Analysis of the spectra yields excited state rotational parameters and vibrational shifts.

The (2-0) (0) and (1) transition frequencies of HD determined to a 10 relative accuracy by Doppler spectroscopy at 80 K.

The Doppler broadened (0) and (1) lines of the (2-0) vibrational band of HD have been measured at liquid nitrogen temperature and at pressures of 2 Pa, with a comb referenced continuous-wave cavity ring-down spectrometer set-up. Transition frequencies of 214905335185 kHz and 217105181898 kHz were derived from 33 and 83 recordings, with corresponding root mean squared deviation of 53 and 33 kHz for the (0) and (1) transition, respectively. This is the first sub-MHz frequency determination of the (0) transition frequency and represents a three order of magnitude accuracy improvement compared to literature.

Gas Cluster Ion Beams as a Versatile Soft-Landing Tool for the Controlled Construction of Thin (Bio)Films.

Surface biofunctionalization with proteins is the key to many biomedical applications. In this study, a solvent-free method for the controlled construction of protein thin films is reported. Using large argon gas cluster ion beams, proteins are sputtered from a target (a pool of pure proteins), and collected on a chosen substrate, being nearly any solid material.

Spectroscopic study of the tunneling dynamics in N-water observed in the O-D stretch region.

The O-D stretch rovibrational spectra of N-DO and N-DOH were measured and analyzed. A combination band involving the in-plane N bending vibration was also observed. These bands were recorded using a pulsed-slit supersonic jet expansion and a mid-infrared tunable optical parametric oscillator.

STARGATE: A new instrument for high-resolution photodissociation spectroscopy of cold ionic species.

Spectroscopy of transient anions and radicals by gated and accelerated time-of-flight experiment is a new spectrometer developed in UCLouvain. This instrument measures high-resolution photodissociation spectra of mass-selected ions by the combination of a time-of-flight spectrometer including a specific gating, bunching, and re-referencing unit with a nanosecond pulsed dye laser, a pulsed deflection, and an energy selector. The ionic species are generated in a supersonic jet expansion by means of an electric discharge or by the impact of electrons coming from an electron gun.

Design and characteristics of a cavity-enhanced Fourier-transform spectrometer based on a supercontinuum source.

We report the in-house fabrication of a high-resolution Fourier-transform spectrometer (FTS) for the spectroscopy of molecules in the gas phase at resolutions down to 0.002 cm working in the spectral range from 5880 cm (1.7 μm) to 15 380 cm (650 nm).

Large cluster ions: soft local probes and tools for organic and bio surfaces.

Ionised cluster beams have been produced and employed for thin film deposition and surface processing for half a century. In the last two decades, kiloelectronvolt cluster ions have also proved to be outstanding for surface characterisation by secondary ion mass spectrometry (SIMS), because their sputter and ion yields are enhanced in a non-linear fashion with respect to monoatomic projectiles, with a resulting step change of sensitivity for analysis and imaging. In particular, large gas cluster ion beams, or GCIB, have now become a reference in organic surface and thin film analysis using SIMS and X-ray photoelectron spectroscopy (XPS).

Structure and dynamics of the radical cation of ethane arising from the Jahn-Teller and pseudo-Jahn-Teller effects.

The pulsed-field-ionization zero-kinetic-energy photoelectron spectrum of CH has been recorded in the region of the adiabatic ionization threshold. The partially rotationally resolved spectrum indicates the existence of several vibronic states of CH with less than 600 cm of internal excitation. The analysis of the rotational structures assisted by ab initio calculations enabled the determination of the adiabatic ionization energy of CH and the investigation of the structure and dynamics of CH at low energies.

New Infrared Bands of the C-Bonded Isomer of OC-NO and Determination of Two Intermolecular Frequencies.

Three combination bands involving intermolecular modes of the most stable isomer of the OC-NO van der Waals complex have been observed, two in the carbon monoxide CO stretch region (∼2150 cm) and one in the ν asymmetric stretch region of NO (∼2223 cm). Vibrational assignment is achieved by comparison with data recently published ( Barclay , A. ; et al.

Detection of a higher energy isomer of the CO-NO van der Waals complex and determination of two of its intermolecular frequencies.

Infrared spectra in the carbon monoxide CO stretch region (∼2150 cm) and in the ν asymmetric stretch region of NO (∼2223 cm) are assigned to the previously unobserved O-bonded form of the CO-NO dimer ("isomer 2"). This van der Waals complex has a planar skewed T-shaped structure like that of the previously observed C-bonded form ("isomer 1"), but with the CO rotated by 180°. The effective intermolecular distance between the centers of mass is 3.

High resolution overtone spectroscopy of the acetylene van der Waals dimer, ((12)C2H2)2.

CW-cavity ring down spectroscopy was used to record in a free jet expansion the spectrum of the absorption band in ((12)C(2)H(2))(2) with origin at 6547.6 cm(-1). It is a perpendicular band and corresponds to 2CH excitation in the hat unit of the T-shaped dimer.

High resolution spectroscopic investigation of a new van der Waals complex: C(2)H(2)-Kr.

The first observation in the near infrared of the (12)C(2)H(2)-Kr van der Waals complex is reported, leading to the determination of rotational constants and the prediction of the 1 0 1 (J'K(a)'K(c)') ← 0 0 0 (J''K(a)''K(c)'') microwave transition occurring at 3.334(4) MHz, useful for astrophysical detection.

Demonstration of cavity enhanced FTIR spectroscopy using a femtosecond laser absorption source.

A proof of principle experiment was performed by recording the cavity enhanced absorption spectrum of the weak b-X transition of molecular oxygen in the atmosphere using a Ti:Sa femtosecond laser as an absorption source and a high resolution continuous scan Fourier transform interferometer. The cavity was mode matched and either continuously scanned or stabilized at the so-called magic point. An optimal rms noise equivalent absorption of 3x10(-7) cm(-1) Hz(-1/2) was reached in the latter case, corresponding to alpha(min)=3x10(-7) cm(-1).

Investigation of the C2H2-CO2 van der Waals complex in the overtone range using cw cavity ring-down spectroscopy.

A slit nozzle supersonic expansion containing acetylene [492 SCCM (SCCM denotes cubic centimeter per minute at STP)] and carbon dioxide (740 SCCM) seeded into Ar (837 SCCM) is investigated using cw-cavity ring-down spectroscopy, in the 1.5 microm range. The C(2)H(2)-CO(2) van der Waals complex is observed around the nu(1) + nu(3) acetylenic band.

(12)C2H2-Ar van der Waals complex.

New theoretical and experimental results on the acetylene-Ar van der Waals complex are presented and the literature is reviewed. New ab initio calculations at the MP2 level were performed using large basis sets with diffuse functions and taking into account the basis set superposition error. It was found that the structure of acetylene is not significantly altered by the complexation and that its vibrational frequencies are only slightly lowered.