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Precision spectroscopy has been the driving force for progress of our physical understanding and still is a promising tool for the investigation of new physics. Molecules offer transitions which allow tests that are not possible in atomic systems. However, usually precision spectroscopy of molecules is challenging due to the lack of cycling transitions for state preparation and state detection. For molecular ions, this obstacle can be overcome by quantum logic spectroscopy, where dissipation for state preparation and detection is provided by a co-trapped atomic ion exploiting the shared eigenstates of motion. Here, we propose a full quantum logic spectroscopy scheme for molecular oxygen ions and theoretically investigate the feasibility of quantum logic-assisted state detection and preparation. Furthermore, we provide coupling rates for a direct single-photon quadrupole excitation of a vibrational overtone transition that can serve as a sensitive reference for tests of a possible variation of the proton-to-electron mass ratio.

The vibrational transitions and the relative abundances of the two isomeric ions H2CNH+ and H2NCH+ generated through electron impact ionisation have been investigated in a noble gas tagging experiment. It could be shown that both species were formed with an abundance of 70 and 30% for H2NCH+ and H2CNH+, respectively. The obtained vibrational bands of the two species have been assigned to vibrational transitions through comparison with the results of ab initio calculations. These computations also predict both species to be moderately polar. The present investigations show that both isomers should be included in chemical model calculations of dark interstellar clouds, protoplanetary disks, star-forming regions as well as planetary atmospheres.

Gas phase vibrational spectra of [C3H3]+ isomers and their fully deuterated isotopologues measured in a cryogenic 22-pole ion trap are presented. The widely tunable free electron laser for infrared experiments, FELIX, was employed to cover the frequency range 500–2400 cm−1, complemented with an OPO/OPA system covering 2800–3400 cm−1. Spectral assignments for both the linear and cyclic isomeric form (H2C3H+ and c-C3H3+, respectively) are made based on various high-level computational studies. The effect of ion source conditions and different precursors (allene and propargyl chloride) for the preferential production of a specific isomer is discussed. The perturbation of the vibrational band position due to complexation with neon in the recorded infrared-predissociation (IRPD) spectra are also reported in this study.

type:Journal Article, Molecular ions in the magnetosphere can be a tracer of fast ion outflows from the deep ionosphere. Statistical properties of molecular ions (O2+/NO+/N2+) in the ring current are investigated based on ion composition measurements (<180 keV/q) by medium‐energy particle experiments‐electron analyzer and low‐energy particle experiments‐ion mass analyzer instruments on board the Arase (Exploration of energization and Radiation in Geospace, ERG) satellite. The investigated period from late March to December 2017 includes 11 geomagnetic storms with the minimum Dst index less than −40 nT. The molecular ions are observed in the region of L = 2.5–6.6 and clearly identified at energies above ~12 keV during most magnetic storms. During quiet times, molecular ions are not observed. The average energy density ratio of the molecular ions to O+ is ~3%. The ratio tends to increase with the size of magnetic storms. Existence of molecular ions even during small magnetic storms suggests that the fast ion outflow from the deep ionosphere occurs frequently during geomagnetically active periods.

Rotational-vibrational transitions of the fundamental vibrational modes of the CN and CN cations have been observed for the first time using a cryogenic ion trap apparatus with an action spectroscopy scheme. The lines P(3) to R(3) of CN and R(1) to R(3) of CN have been measured, limited by the trap temperature of approximately 4 K and the restricted tuning range of the infrared laser. Spectroscopic parameters are presented for both isotopologues, with band origins at 2000.7587(1) and 1970.321(1) cm, respectively, as well as an isotope independent fit combining the new and the literature data.

The essential material constant that determines the bulk of the stopping power of high energy projectiles, the mean excitation energy, is calculated for a range of smaller molecular ions using the RPA method. It is demonstrated that the mean excitation energy of both molecules and atoms increase with ionic charge. However, while the mean excitation energies of atoms also increase with atomic number, the opposite is the case for mean excitation energies for molecules and molecular ions. The origin of these effects is explained by considering the spectral representation of the excited state contributing to the mean excitation energy.

Interstellar hydrides--that is, molecules containing a single heavy element atom with one or more hydrogen atoms--were among the first molecules detected outside the solar system. They lie at the root of interstellar chemistry, being among the first species to form in initially atomic gas, along with molecular hydrogen and its associated ions. Because the chemical pathways leading to the formation of interstellar hydrides are relatively simple, the analysis of the observed abundances is relatively straightforward and provides key information about the environments where hydrides are found. Recent years have seen rapid progress in our understanding of interstellar hydrides, thanks largely to FIR and submillimeter observations performed with the Herschel Space Observatory. In this review, we discuss observations of interstellar hydrides, along with the advanced modeling approaches that have been used to interpret them and the unique information that has thereby been obtained.

A significant number of electrostatic ion-storage rings have been built since the late 1990s or are currently in their construction or commisioning phases. In this short contribution, we attempt to supply an overview of these different facilities, while we also mention a selection of the electrostatic ion-beam traps that has been developed through the same time period and by some of the same research groups.

In this project we have investigated the generation, interaction and energetic impact of electrosprayed nanodroplets and molecular ions, covering continuously the projectile size range from 1 nm up to hundreds of nm. The 1-20 nm size range is of great interest to achieve variable specific impulse (Isp) from 100 s to 1000 s in drop-based electrical propulsion, while pure molecular ion emission enables higher Isp. The resulting knowledge is directly applicable to electrospray thrusters/electric propulsion), and will lead to new opportunities in other fields such as MEMS and IC fabrication. The specific research problems tackled during this projects and accomplishments include: the development of a basic electrospray beam model, and measurements of the spreading of the beam at varying temperature; the experimental characterization and typical thruster surfaces bombarded by electrosprayed nanodroplets, and a molecular dynamics study of the physics of nanodroplet impact; the extension of the minimum size of electrosprayed nanodroplets, and the exploration of energetic propellants for propulsion and sputtering; and molecular dynamics simulations of the fragmentation and emission of ions from ionic liquids., The original document contains color images.

This project was superseded and replaced by another ARO-funded project of the same name, which is still continuing. The goal of this project was to explore ultracold collisions and chemistry between atoms and ions, to enable a novel cooling method, proposed by our group, for producing ultracold molecular ions. During this effort period, we experimentally and theoretically studied ultracold chemistry and collision in two important systems Ca + Yb+ and Ca + Ba+. As a result of this work, we have a gained a clearer understanding of both the fundamental physics important for these collisions and the requirements for producing stable, long-lived ultracold ion-neutral systems. Building on this work, we have recently performed a proof-of-principle experiment that has demonstrated sympathetic cooling of both the translational and vibrational motion of BaCl+ molecules through collisions with ultracold gases. The results of this experiment are very promising and indicate that the proposed cooling method is as efficient as expected. Work now has turned to optimizing the experimental system for the production of ultracold, ground-state molecular ions., The original document contains color images.

Storage and cooling of highly charged ions require ultra-high vacuum levels obtainable by means of cryogenic methods. We have developed a linear Paul trap operating at 4 K capable of very long ion storage times of about 30 h. A conservative upper bound of the H 2 partial pressure of about 10 -15 mbar (at 4 K) is obtained from this. External ion injection is possible and optimized optical access for lasers is provided, while exposure to black body radiation is minimized. First results of its operation with atomic and molecular ions are presented. An all-solid state laser system at 313 nm has been set up to provide cold Be ions for sympathetic cooling of highly charged ions. © 2012 American Institute of Physics.

We present quantum-mechanical studies on above-threshold ionization of molecular ions in two and three dimensions. The momentum distributions show signatures of interfering emissions from the molecular centers. These structures deviate from a simple double-slit model that ignores the electron-ion interaction, but they are reproduced by an eikonal model. Such distortions of the interference pattern are partly responsible for the absence of clear interference patterns in the angle-integrated electron energy spectra. © 2011 American Physical Society.

The objective of this effort has been to develop a novel instrument for the spectroscopic study of molecular ions, which we call SCRIBES (Sensitive, Cooled, Resolved, Ion BEam Spectroscopy). The instrument has been constructed during the period of this award, and ultrasensitive spectroscopic techniques (including NICE-OHMS) have been employed in an effort to obtain an absorption spectrum of the N2+ molecular ion. While the SCRIBES instrument is still being commissioned, this work has already led to the development of an unexpected and exciting approach for molecular ion spectroscopy: cavity-enhanced velocity modulation spectroscopy., AFRL-OSR-VA-TR-2011-0252

A near-ultraviolet (NUV) spectrograph (320-460 nm) was flown on the EXL98 aircraft sprite observation campaign during July 1998. In this wavelength range video rate (60 fields/sec) spectrographic observations found the NUV/blue emissions to be predominantly N2(2PG). The negligible level of N+2 (1NG) present in the spectrum is confirmed by observations of a co-aligned, narrowly filtered 427.8 nm imager and is in agreement with previous ground-based filtered photometer observations. The synthetic spectral fit to the observations indicates a characteristic energy of 1.8 eV, in agreement with our other NUV observations., In press, Journal of Geophysical Research. Sponsored in part by National Aeronautics and Space Administration (NASA) Grants no. NAG5-5172, NAG5-5125 and NAG5-5019. Prepared in collaboration with Los Alamos National Lab, Los Alamos, NM; Geophysical Institute, University of Alaska Fairbanks, Fairbanks, AK; and SRI International, Menlo Park, CA.

This project centered on the development of new methods to trap, cool, and detect polar molecules, with potential application across a broad range of subfields. Progress was made on several inter-related fronts. A new, simple and general source for slow and cold molecular beams was developed. This source was demonstrated to work, with several molecular species, in two regimes: one with low velocity but also low flux, and another with higher velocity but also orders of magnitude greater brightness. The latter source is particularly suitable for precision spectroscopy and collision studies; both show promise as sources for loading into traps. In parallel, we worked towards construction of a high-power microwave resonator, which can be used as a novel type of trap for polar molecules; and we devised and began to implement a new method for laser cooling of molecules from the beam. We also developed a set of ideas for trapping polar molecules and/or molecular ions near the surface of a cryogenic chip. Integration with superconducting devices on the chip holds great promise as an architecture for large-scale quantum computing, as well as for highly sensitive detection of molecules with precise spectral fingerprinting., Federal Purpose Rights, The original document contains color images.

Our program specializes in the spectroscopic characterization of molecular ions and reactive intermediates in ion-molecule reactions, and is closely integrated with ongoing activities at the AFRL Space Vehicles Directorate to determine the temperature dependence of ion-molecule and ion-ion reaction kinetics which are important in high-velocity (e.g., scramjet) combustion and re-entry plasma. Our role in this collaboration was to provide experimental benchmarks for bond energies, structures, and stationary points in the potential energy profiles for reactions that are relevant models for ion-assisted combustion of hydrocarbons., The original document contains color images. All DTIC reproductions will be in black and white.

The dissociative recombination of OPCI(+) and OPCI(2)(+) has been studied at the storage ring CRYRING. The rate constants as a function of electron temperature have been derived to be 7.63 x 10(-7)(T(e)/300)(-0.89) and > 1/2 x 10-6 (T(e)/300)(1.22) cm(3) s(-1). respectively. The lower limit quoted for the latter rate constant reflects the experimental inability to detect all of the reaction products. The branching fractions from the reaction have been measured for OPC1+ at approx. 0 eV interaction energy and are determined to be N(O+P+C1)=( 16 7), N(O+PC1)=( 16 3)% and N(OP+Cl)=(68 5)%. These values have been obtained assuming that the rearrangement channel forming P+CIO is negligible, and ah initio calculations using GAUSSIAN03 are presented for the ion structures and energetic to support such an assumption. Finally, the limitations to using heavy ion storage rings such as CRYRING for studies into the dissociative recombination of large singly charged molecular ions are discussed., Published in the Journal of Chemical Physics, v128 n134308-1 through 134308-7, 2008. Prepared in collaboration with Boston College, Chestnut Hill, MA, under contract no. FA8718-04-C-0006, and with Stockholm University, Stockholm, Sweden.

This report results from a contract tasking Stockholm University as follows: The Grantee will investigate the measurements of branching ratios in recombination of polyatomic molecular ions. It is proposed to study not only the rates of dissociative recombination of ions important for plasma-enhanced combustion but also the neutral product distributions. Deuterated molecules and peak fitting procedures will be applied to enhance the resolution. The proposed measurements will add greatly to the knowledge base in this unexplored field, yielding answers to the questions outlined above and serving as important inputs to the Air Force combustion models.

This project addressed the development of a new class of metal/organic supramolecular polymers, which are prepared by the self-assembly of ditopic ligands and appropriate metal ions. The ditopic ligand consists of two 2,6-bis(1'-methyl-benzimidazolyl)pyridine ligands, which are connected to each other by either a conjugated poly(p-phenylene ethynylene) (PPE) core or a poly(p-xylyene) (PPX) core. The metal/organic supramolecular polymers based on ditopic poly(p-xylyene) macromonomers were investigated as easy-to-process high-temperature-resistant materials. We demonstrated that these supramolecular materials are indeed easily processably in common organic solvents and that their thermal stability is very similar to that of common (but intractable) poly(p-xylenes). In addition, investigations of metallo-supramolecular polymers based on the ditopic poly(p-phenylene ethynylene) macromonomers have demonstrated the potential of these systems as sensors for chemical warfare agents. In particular, we have shown that these materials and selected derivatives exhibit significant changes in fluorescence in the presence of organophosphates and that different organophosphates show different responses., The original document contains color images.

Molecular dynamics (MD) simulation has been used to probe ion-conduction mechanisms in crystalline LiPF6.PEO6 for smectic- and nematic-ordered models of methyl-terminated short-chain monodisperse poly(ethylene oxide) chains with the formula CH3-(OCH2CH2)23-OCH3; Mw = 1059. The effect of aliovalent substitution of the PF6- anion by ca. 1% SiF62- has also been studied. External electric fields in the range 3-6 x 106 V m-1 have been imposed along, and perpendicular to, the chain direction in an effort to promote ion transport during the short timespan of the simulation. Ion-migration barriers along the polymer channel are lower for the nematic models than for the smectic, with anions migrating along the channels more readily than Li-ions. Ion mobility within the smectic interface could also be confirmed, but at a higher field-strength threshold than along the chain direction. Li-ion migration within the smectic plane appears to be suppressed by ion pairing, while Li-ion transport across the smectic gap is facilitated by uncoordinated methoxy end-groups. Interstitial Li-ions introduced into the PEO channel through SiF62- doping are also shown to enhance Li-ion conduction.

We review techniques to prepare, evaluate and apply sets of cross section and transport data for negative ions that are required for the modeling of collisional non-equilibrium plasmas used for processing of microelectronic circuits. We collect and discuss the transport coefficients and cross section sets. We have compiled data for negative ions in CF4 and CF4-related negative ions in rare gases. In addition, we consider data for F- and CF3- in rare gases. Furthermore, we analyze the cross sections of halogen negative ions in rare gases and other molecules. This is followed by the data for SF6 related ions in SF6 and in rare gases. The cross section for scattering of O- in O-2 has been derived from the transport data and used to make calculations of the transport properties. Finally we give a brief discussion of the availability of the data for H- ions in H-2. We have derived cross sections in several cases but the basic aim is to show the basic features of transport coefficients. In particular we discuss the need to represent properly some details such as the non-conservative nature of transport coefficients and the anisotropy of diffusion. Application of approximate theories and representations of cross sections are also discussed.

We demonstrated an approach toward the design of starburst C60-keto-DPAF assembly by applying a combination of a starburst macromolecular configuration with C60 as the core center, which is encapsulated by multiple bulky groups leading to the increase of intermolecular separation and aggregation barrier. Molecular compositions of the resulting triad and pentads were clearly confirmed by MALDI-MS (positive ion) detection of protonated molecular mass ions. Both structural isomers, 3a and 3b exhibited nonlinear optical transmittance reduction responses in femtosecond (fs) region with a lower transmittance % value for the latter at the high laser power above 80 GW/sq cm. It was attributed to larger fs 2PA cross-section values of 3a and 3b than that of 2 in the same concentration and, apparently, correlated to a higher number of DPAF-C9 subunits in the structure of 3., Submitted for publication in the Journal of Materials Chemistry. Prepared in cooperation with University of Massachusetts, Lowell, MA. Prepared in collaboration with Air Force Research Laboratory (AFRL), Wright-Patterson AFB, OH.

This paper presents the methodology to generate beams of ions in single quantum states for bimolecular ion-molecule reaction dynamics studies using pulsed field ionization (PFI) of atoms or molecules in high-n Rydberg states produced by vacuum ultraviolet (VUV) synchrotron or laser photoexcitation. Employing the pseudocontinuum high-resolution VUV synchrotron radiation at the Advanced Light Source as the photoionization source, PFI photoions (PFI-PIs) in selected rovibrational states have been generated for ion-molecule reaction studies using a fast-ion gate to pass the PFI-PIs at a fixed delay with respect to the detection of the PFI photoelectrons (PFI-PEs). The fast ion gate provided by a novel interleaved comb wire gate lens is the key for achieving the optimal signal-to-noise ratio in state-selected ion-molecule collision studies using the VUV synchrotron based PFI-PE secondary ion coincidence (PFI-PESICO) method. The most recent development of the VUV laser PFI-PI scheme for state-selected ion-molecule collision studies is also described. Absolute integral cross sections for state-selected H+2 ions ranging from v+=0 to 17 in collisions with Ar, Ne, and He at controlled translational energies have been obtained by employing the VUV synchrotron based PFI-PESICO scheme., Published in The Journal of Chemical Physics, v125 p132306-1 through 132306-14, 2006. Prepared in collaboration with Boston College, Newton, MA, and University of California, Davis, CA. Sponsored in part by Air Force Office of Scientific Research (AFOSR) contract no. F49620-99-1-0234; National Science Foundation (NSF) grant no's. CHE-0517871 and ATM-0317422; and Department of Energy (DOE) grant no. DE-FG02-02ER15306. The original document contains color images.

Quantum computing; Quantum phenomena in superconducting devices; Phase-space and charge-space Nanodevices; Dissipation and Decoherence in mesoscopic systems; Macroscopic quantum coherence in physical systems, including: NMR, Nuclear Magnetic Resonance; Quantum dots; Ions; Magnetic systems; BEC, Bose Einstein Condensation., s of papers presented at the International Workshop on Macroscopic Quantum Coherence and Computing (MQC2) (4th) held in Naples, Italy on 7-10 Jun 2004.

In order to improve the geometrical characterization of molecular ions using the Coulomb Explosion Imaging method, we discuss the need to include wake effects in a full description of the interactions felt by the swift dissociated atomic ions moving through thin foils. Comparison of simulations and experimental results for the structure of diatomic (HD+) and triatomic (CH2+) molecular ions is significantly improved when including the polarization effects induced in the target by the passage of swift ions.

In order to improve the geometrical characterization of molecular ions using the Coulomb Explosion Imaging method, we discuss the need to include wake effects in a full description of the interactions felt by the swift dissociated atomic ions moving through thin foils. Comparison of simulations and experimental results for the structure of diatomic (HD+) and triatomic (CH2+) molecular ions is significantly improved when including the polarization effects induced in the target by the passage of swift ions.

The hydrogen neutral beams are widely used to diagnose the plasma in magnetic fusion devices. The beams are extracted from the plasma generated by a plasma source, accelerated to desired energy and subsequently neutralized in a gas target. The critically important characteristics of the plasma source are the composition and the source lifetime. A presence of the molecular ions in the plasma results in appearing of atoms in the beam with energies E, E/2, and E/3, where E is the determined by accelerating voltage (E=eU). For example, the plasma sources of the diagnostic injectors developed for TEXTOR and TCV tokamaks 1,2, which are based on RF-discharge, has a long enough lifetime (many thousands shots) for a pulse duration 2-10 sec. At the same time, the proton fraction in the RF-plasma is about only 60% by current 2,3., Pub. in International Conference on Phenomena in Ionized Gases (26th), v4 p127-128, July 2003. Prepared in cooperation with Budker Institute of Nuclear Physics, Novosibirsk, Russia; Association EURATOM KFA, Juelich, Germany. This article is from ADA421147 International Conference on Phenomena in Ionized Gases (26th) Held in Greifswald, Germany on 15-20 July 2003. Proceedings, Volume 4

The crucial AFOSR support of this prestigious international meeting, the XIXth Conference on the Dynamics of Molecular Collisions, included participant support for invited speakers and other presenting authors. The AFOSR support, under award number F49620-03-1-0286, was $10,000, with a duration of 5/1/2003 - 12/31/2003. AFOSR has traditionally been generous in support of this meeting, as it draws a broad spectrum of the top researchers and young talent across several areas of direct interest to the AFOSR mission. The invited speakers included several with AFOSR funding, and the invited and contributing participants are drawn from both educational institutions and national laboratories., Presented at the Conference on the Dynamics of Molecular Collisions (XIXth) held in Tahoe City, CA on 13-18 Jul 2003.

We report the results of the application of the semi-classical Deutsch-Mark (DM) formalism to the calculation of the absolute electron-impact ionisation cross section of the molecular ions H-2(+), N-2(+), O-2(+), CD+, CO+, CO2+, H3O+/D3O+, and CD4+ for which experimental data have been reported. Where available, we also compare our calculated cross sections with calculated cross sections using the BEB method. The level of agreement between the experimentally determined and the calculated cross section is satisfactory only in a few cases. In most cases, the calculated cross sections exceed the measured cross sections, in some cases significantly, which is not surprising in view of the experimental complications in measuring ionisation cross sections of molecular ions due to the presence of competing channels for the formation of fragment ions such as dissociative excitation versus dissociative ionisation. (C) 2002 Elsevier Science B.V. All rights reserved.

Work carried out under this grant is summarized. In particular, the prediction of a novel ferroelectric material NaCaF3 is described and its predicted properties summarized. First principles calculations on a wide range of ionic molecular solids are summarized. These range from studies on halide perovoskites to work on alkaline earth silicates. In most cases very reasonable accord with experiment is achieved. One notable exception is the class of alkali cyanides which clearly require more sophisticated treatment. The basic theoretical approach is a combination of a Gordon-Kim modified electron gas theory with the quantum chemistry GAUSSIAN code to handle covalently bonded molecular ions. As indicated, this parameter free treatment reproduces experimental phase diagrams with good accuracy.

This report results from a contract tasking Stockholm University as follows: CRYRING, a synchrotron/heavy-ion storage ring facility, has proved to be a powerful tool for measurements of branching ratios in recombination of polyatomic molecular ions. However, there are important questions that still need to be addressed for organic ions such as: 1)Is there a mass limit at which fragmentation decreases or even vanishes and most or all of the electron energy is converted to internal degrees of freedom? 2) What is the order, n, of the dissociation shown in reaction? 3)Is the fragmentation process instantaneous? Or is there a delay in the break-up process? For a small inorganic ion such as H20+ the break-up process is most likely instantaneous, but whether this is also true for larger organic ions is unknown. 4)IS the break-up process a one-step or a multi-step process? Prediction of the products of dissociative recombination is very difficult. It is here proposed to study not only the rates of dissociative recombination of ions important for plasma-enhanced combustion but also the neutral product distributions. Experiments with many important hydrocarbon ions (the benzene cation, for example) will be performed. Another problem concerns the resolution of the solid-state particle detector, because well-resolved mass peaks facilitate the measurement of product branching ratios. Deuterated molecules and peak fitting procedures will be applied to enhance the resolution. The proposed measurements will add greatly to the knowledge base in this unexplored field, yielding answers to the questions outlined above and serving as important inputs to the Air Force combustion models.

The goal of this project was to develop an ion spectrometer capable of making absorption measurements on ions using cavity ring-down spectroscopy (CRDS). As part of our continuing goal of detecting ion products from ion-molecule reactions, we have successfully used CRDS to measure the vibronic absorption spectra of various small ions and radicals generated by a pulsed discharge nozzle. These spectra give information about the number densities and temperatures of the ions and radicals. Currently, our setup consists of a pulsed discharge nozzle that produces high concentrations of radicals and ions arranged perpendicular to the optical cavity made from two highly reflective mirrors. To date, we have obtained the absorption spectrum of N2(+) and CN as well as several atomic species.

We have simulated the spatial evolution and energy loss of the fragments that result when swift molecular ions dissociate inside solid targets. In our calculations we have considered that these fragments undergo the following interactions: Coulomb repulsion (among like charged particles), stopping and wake forces (due to electronic excitations induced in the target), and nuclear scattering (with the target nuclei). We study the case of silicon targets irradiated with boron molecular or atomic ions; our results show that the main differences in the energy and spatial distributions of molecular fragments or atomic ions appear at shallow regions, and these tend to disappear at deeper depths.

We have simulated the spatial evolution and energy loss of the fragments that result when swift molecular ions dissociate inside solid targets. In our calculations we have considered that these fragments undergo the following interactions: Coulomb repulsion (among like charged particles), stopping and wake forces (due to electronic excitations induced in the target), and nuclear scattering (with the target nuclei). We study the case of silicon targets irradiated with boron molecular or atomic ions; our results show that the main differences in the energy and spatial distributions of molecular fragments or atomic ions appear at shallow regions, and these tend to disappear at deeper depths.

Initially, we developed an ion spectrometer that could be used to study the spectroscopy and reactivity of small ions. For this purpose we characterized the discharge source, forming ions by combining an electrical discharge with a supersonic expansion from a pulsed nozzle. After expanding into a vacuum chamber, the ions were detected using cavity ring-down spectroscopy (CRDS), allowing the population of individual states to be determined on an absolute basis. The CRDS detection of the ions from this source was tested with N2+ by probing the B(2) sum sigma(+) - X(2) sum sigma (+)g electronic band system. We are also using Hadamard transform time-of-flight mass spectrometry as the basis for producing an instrument that could be used to analyze and identify the components of potentially contaminated samples.

A series of hyperthermal energy, ion/surface scattering experiments were performed. These studies examined and characterized some of the many processes occurring in energetic gas/surface collisions. In the scattering of Ne+ on Si(001), the precise amount of momentum, transferred to the surface upon collision, was measured under various conditions. Models that incorporate image charge interactions and inelastic energy loss were successfully applied to simulate the data. The first measurement of atom abstraction at an oxide surface was recorded in the scattering of NO+ on O/Al(111). Measurement of the product yield and energy distribution as a function of incident energy revealed the detailed reaction mechanism. The growth and erosion of SiO2 thin films under O+ bombardment was studied. Isotopic labeling experiments combined with mass-, energy-, and angular-resolved detection provided compelling evidence for a direct Eley-Rideal abstraction of adsorbed oxygen by incident O+ ions. This reaction pathway competes directly with sputtering channels in the formation of scattered O2- and SiO+. The conclusions from this work help in the modeling of spacecraft interactions with the LEO environment, e.g., vehicle drag, spacecraft charging, oxidation/degradation of exposed surfaces, and the formation of signatures.

We analyse the effects on the stopping power due to the geometrical structure of swift Bn+ (n = 2-6) ions incident on amorphous carbon targets. We use the dielectric formalism to describe both the interaction of the projectile with the stopping medium and the vicinage effects on the atomic ions resulting from the dissociation of each Bn+ ion. The variation of the energy loss with the temporal evolution of the relative positions of the atomic ions, due to Coulomb explosion, has also been taken into account. The calculated stopping power ratio for each Bn+ ion reproduces fairly well the main trends, as a function of the dwell time, observed in the available experimental data. The differences among the stopping power ratios of the Bn+ ions disappear as the number of atomic ions, n, increases.

We analyse the effects on the stopping power due to the geometrical structure of swift Bn+ (n = 2-6) ions incident on amorphous carbon targets. We use the dielectric formalism to describe both the interaction of the projectile with the stopping medium and the vicinage effects on the atomic ions resulting from the dissociation of each Bn+ ion. The variation of the energy loss with the temporal evolution of the relative positions of the atomic ions, due to Coulomb explosion, has also been taken into account. The calculated stopping power ratio for each Bn+ ion reproduces fairly well the main trends, as a function of the dwell time, observed in the available experimental data. The differences among the stopping power ratios of the Bn+ ions disappear as the number of atomic ions, n, increases.

We report measurements of the [C II] 157.74 microns fine-structure line in a sample of seven ultraluminous infrared galaxies (ULIGs) with the Long Wavelength Spectrometer on the Infrared Space Observatory. The [C II] line is an important coolant in galaxies and arises in interstellar gas exposed to far-ultraviolet photons; in ULIGs, this radiation stems from the bursts of star formation and/or from the active galactic nuclei that power the tremendous infrared luminosity. The [C II] 158 micronline is detected in four of the seven ULIGs; the absolute line flux (about a few times 10(exp -20) W cm(expo -2) represents some of the faintest extragalactic [C II] emission yet observed. Relative to the far-infrared continuum, the [C II] flux from the observed ULIGs is approx. 10% of that seen from nearby normal and starburst galaxies. We discuss possible causes for the [C II] deficit, namely (1) self-absorbed or optically thick [C II] emission, (2) saturation of the [C II] emission in photodissociated gas with high gas density n or with a high ratio of incident UV flux G(sub 0) to n or (3) the presence of a soft ultraviolet radiation field caused, for example, by a stellar population deficient in massive main-sequence stars. As nearby examples of colliding galaxies, ULIGs may resemble high-redshift protogalaxies in both morphology and spectral behavior. If true, the suggested [C II] deficit in ULIGs poses limitations on the detection rate of high-z sources and on the usefulness of [C II] as an eventual tracer of protogalaxies., Prepared in collaboration with NASA Goddard Space Flight Center, Greenbelt, MD; Department of Astronomy, University of Maryland, College Park, MD; Department of Physics, Towson University, Towson, MD; Institut d' Astrophysique Spatiale, Universite de Paris, France; IPAC, California Institute of Technology, Pasadena, CA; Harvard-Smithsonian Center for Astrophysics, Cambridge, MA; Astronomy Department, Cornell University, Ithaca, NY; and Queen and Mary Westfield College, University of London, London, UK. Published in The Astrophysical Journal, v504, pLL11-L15, 1 Sep 1998.

The object of this research is to characterize the energetics, spectroscopic properties, and elementary chemical reactions of molecular ions. The approach used will exploit recent developments in ab initio molecular quantum mechanics. Some of the systems to be studied include the species CF sub n and (n=1-3), SF sub n and (n=1-7), (HNO3)n (H2O)m, (ClNO3), (H2SO4)m (HNO3)n (H2O)o, and + CH4.

Following our previous compilations [IPPJ-AM-45 (1986), NIFS-DATA-7 (1990), NIFS-DATA-20 (1993)], bibliographic information on experimental and theoretical studies on electron transfer processes in ion-ion/atom/molecule collisions is up-dated. The references published through 1954-1996 are listed in the order of the publication year. For easy finding of the references for a combination of collision partners, a simple list is provided.

The overall objective of the Phase I work was to evaluate certain key technical aspects of a proposed Imaging Mass Detector. The proposed instrument consists of a time of flight fission fragment plasma desorption mass spectrometer with a novel imaging system for locating the position on the specimen from which molecules are desorbed. Mass Spectrometers which utilize fission fragments to plasma desorb molecular ions from samples have been characterized in the scientific literature and did not require further development. The unique untested principle of the proposed system was that of tracking the fission fragments and combining the mass and spatial information to develop mass images of specimens. The primary task of this Phase I program was, therefore, to identify, test, and evaluate the most suitable spatial detector technology. The main results of the investigation has been to demonstration that such a design is feasible and to provide a layout of a plausible system.

Controlled radical polymerizations can be achieved by using either unimolecular or bimolecular exchange between growing radicals and dormant chains. Dormant chains can be represented as either covalent species or organometallic compounds. Systems based on alkoxyamines, organochromium, organoaluminum compounds, and alkyl iodides are discussed in detail. In many systems, straight semilogarithmic plots indicate a constant number of growing radicals. A linear increase of molecular weights with conversion indicates a constant number of chains capable of growth but being predominantly in the dormant state. Some of these systems can be used in the synthesis of block copolymers and for end-functionalization. (AN)

In this paper we present the results of our mass spectrometric investigations for van der Waals clusters of 2-methoxyethanol and 2- ethoxyethanol. The cluster mass spectra were acquired for a variety of expansion conditions and electron energies. The protonated alkoxyethanol cluster ions (AE)nH(+) form the dominant cluster ion series. A number of fragment ions, that may arise from an unprotonated and/or a protonated alkoxyethanol molecular ion, were solvated by additional alkoxyethanol molecules. The (AE)n(H20)mH(+) ions were observed with significant intensities only for n >/= 5 in neat as well as mixed alkoxyethanol/water expansions. It was also found that (AE) n (H20)m H(+) cluster ions which satisfy the condition n = 2 (m + 2), for m = 1 and 2, have enhanced ion intensities. The various models that may explain the behavior of (AE)n(H20)mH(+) are discussed.

Electron impact ionization of large neutral clusters composed of simple olefinic molecules (ethene, 1,1-difluoroethene and propene) display highly anomalous ion intensity distributions. These cluster ion distributions typically exhibit a magic number at n=4, for cluster ions of the type (M) sub n +, where M is an olefinic molecule. The explanation which best explains this observation is that these small 'cluster' ions are in actuality covalently bound molecular ions formed by sequential ion-molecule association (polymerization) reactions which have occurred within the cluster ion. This size dependent cluster chemistry is accounted for by kinetic bottle-necks which occur in the ionic chain growth reactions and which terminate with the formation of cyclic molecular ions (i.e. cyclopentanes and cyclohexanes ions). The condensed phase counterparts of these intra-cluster reactions are the free cationic polymerization reactions initiated by radiolysis of bulk samples of the olefins. In addition to reviewing our own efforts in this field, we will discuss previous work on cationic polymerization which is relevant to the new chemistry we have observed within clusters of olefinic molecules. We also will present work concerning acetylene and methylacetylene cluster ions where we also observe similar intra-cluster...., Pub. in International Reviews in Physical Chemistry, p002-020 1993.

Infrared multiple photon dissociation (IRMPD) spectra in the 9.2 - 10.8 micrometers wavelength range have been obtained for the protonated molecular ions of 3-bromopropene and gallium hexafluoroacetylacetonate, using one and two lasers. Use of a low power tunable C02 laser and a modified White- type multipass FTICR cell has helped to overcome some limitations of this technique, including a limited tuning range and/or low output power in one-laser experiments. Comparisons between the ion spectra and those of the corresponding neutral species are made.... Infrared spectra, Ionic spectra, Gaseous ions, Infrared multiple photon dissociation, Fourier transform ion cyclotron resonance mass spectrometry.

Work over a three year period on the optical and dielectric properties of a sequence of ionic molecular solids such as K2SeO4, KNO, and NaNO2 is described. This work had both experimental and theoretical components. Principally the experiments used light scattering and birefringence to monitor structural and optical changes associated with solid-solid phase transitions. Theoretical studies concentrated on developing a unified theory of the ionic interactions in these systems which resulted in parameter free molecular dynamics simulations which closely reproduced the observed transition and structural behavior of these increasingly complex systems. Ferroelectrics, Phase, Transitions, Ionic, Molecular, Solids

New measurements of the stimulated recombinations of electrons and protons to form hydrogen atoms in states n=11, 12 and 13 are presented. Measurements have also been made for the stimulated recombination of electrons and He+ to form n=15 and n=16 states. These cross sections show structure due to singlet and triplet capture. The effects of laser radiation on the dissociative recombination of molecular ions H3+ have been examined and the results are reported.

Optical emission cross section and excitation function for the D2 pi g --> A2 pi u bands of N2+ produced by electron impact on N2 molecules have been measured. Analysis of the results indicates the difference in the production mechanisms for the N2+ (D2 pi g) state as compared to the production mechanisms for the N2+ (A2 pi u) and N2+ (B2 sigma + u)2 states.

The main objective of this program was to investigate the possibility of developing tunable solid state lasers based on complexes of Transition Metal Ions in their highest valency state or equivalently do configuration. This is a class of materials, often referred to as phosphors with strong absorption bands in the UV, and thus well suited for excimer laser pumping. We have found that, contrary to initial arguments, Excited State Absorption processes are very strong and overlapping the emission spectrum. Indications are that octahedral complexes, rather than tetrehedral may have a greater chance, especially in inorganic glasses. Additionally photochromic effects in BGO are reported and a study of non-radiative processes in broad band emitters, the later showing the inadequacy of present theoretical approach. Solid State Laser, Excited State Absorption Photochromizm, Non-radiative processes