In spite of the stablility (lack of reactivity) of diamond powder, I have developed a method for tethering alkyl chains and polymers to deuterium/hydrogen-terminated diamond. One method is through ether linkages via thermolysis of di-tert-amyl peroxide (DTAP). This reaction with DTAP has also been applied to grow polymers on the diamond surface. The other method is atom transfer radical polymerization (ATRP), which was applied to grow polystyrene at the surface of diamond. Both polystyrene-modified diamond and sulfonated polystyrene-modified diamond can be prepared by either method, and can be used for solid phase extraction. Diamond stationary phases are stable under basic conditions, which is not the case for silica-based stationary phases. Surface characterization was performed by X-ray photoelectron spectroscopy (XPS), time-of-flight secondary ion mass spectrometry (ToF-SIMS) and diffuse reflectance Fourier transform infrared spectroscopy (DRIFT). While the main focus of my graduate research has been the surface modification of diamond, I also describe other projects on which I have worked. The use of radical-based processes for modifying diamond is related to a different radical-based synthesis of monolayers or polymers I performed by scribing silicon (Siscr). After preparation of homogeneous olefin-terminated monolayers on scribed silicon made from 1,9-decadiene and chemisorption of Grubbs' catalyst, ring-opening metathesis polymerization (ROMP) of norbornene was demonstrated. These surfaces were characterized by XPS and ToF-SIMS. I also investigated the extent of PDMS oligomers transfer onto different surfaces with a wide range of hydrophobicities, using an uninked, unpatterned PDMS stamp. The effect of surface free energy on PDMS transfer in microcontact printing was investigated and the relationship between the amount of PDMS in ToF-SIMS spectra and the surface tensions of initial surfaces was revealed. Therefore, PDMS transfer can be applied as a probe of surface free energies using ToF-SIMS, where PDMS preferentially transfers onto more hydrophilic surface features during stamping, with little transfer onto very hydrophobic surface features. In much of my thesis work, I performed multivariate analysis of my data, especially of my ToF-SIMS data. Such chemometrics methods include principle components analysis (PCA), partial least squares (PLS) cluster analysis, and multivariate curve resolution (MCR). I also applied these tools to analyze electrospray ionization (ESI) mass spectrometry data from a lipidomics study.

En aquesta tesi, proposem la fabricació y la caracterització d’un microconcentrador de gasos, per ser acoblat amb un microsistema de detecció, per millorar el seu límit de detecció davant els gasos tòxics. Aquest estudi s’aplica especialment al benzè, que es un compost d’alta cancerigenitat. El preconcentrador proposat esta basat en estructura plana, que, es una opció de fabricació més simple y permet una millor aïllament tèrmic amb el resta d’unitats del microsistema, qu’els estructures 3D proposats a la literatura. No obstant, els factors de concentració obtinguts amb l’estructura plana queden generalment més baixos, per causa de la menor quantitat de material absorbent que pot acollir. En aquesta tesis, es va superar aquest problema mitjançant l’utilització del carboní actiu, un adsorbent d’alta capacitat d’adsorció, així com l’optimització de les condicions de funcionament del dispositiu. Finalment, acoblant el microconcentrador amb un micro-cromatògraf, vam aconseguir una detecció sensible y selectiva del benzè en barreja amb altres volàtils a l’aire. / The present thesis focuses on the fabrication and characterization of a gas microconcentrator for to be coupled with a detection microsystem, in order to lower its detection limit towards toxic gases and vapours in contaminated areas. This study was more especially applied to the preconcentration of benzene, a cancerigenic compound at low ppb level. A preconcentrator based on a planar structure was proposed regarding its simpler fabrication, better thermal insulation and lower power consumption, compared to the 3D structures proposed conventionally in literature. In order to obtain higher concentration factors with such structure, its small size was compensated by using a high adsorption capacity adsorbent such as activated carbon as well as the optimization of the preconcentration conditions of the device. Finally, the microconcentrator was validated as injection unit when coupled with a microchromatographic system, where a sensitive and selective analysis of benzene in mixture with other VOCs was achieved.

When an atomic nucleus undergoes fission, two fragments with different mass and kinetic energy are emitted. The highly unstable fission fragments (FFs) evaporate prompt neutrons soon after the nucleus splits. A precise measurement of both, the mass yield distribution of the FFs and the average prompt neutron emission, $\bar{\nu}$, is important not only for current nuclear technologies but also for the development of future technologies such as Generation IV nuclear power plants. Moreover, the experimental determination of the mass yield distributions, both pre- and post-neutron emission, is valuable for testing fission models. Additionally, a precise measurement of the average neutron multiplicity as a function of the FFs mass, <img src="http://www.diva-portal.org/cgi-bin/mimetex.cgi?$%5Cbar%7B%5Cnu%7D(A)$" data-classname="equation" data-title="" />, is crucial in the understanding of how the excitation energy is shared between nascent FFs.  The VElocity foR DIrect particle identification spectrometer (VERDI) is designed to achieve pre- and post-fission mass distributions with resolutions between 1-2 u. VERDI is a double-energy double-velocity instrument that consists of two arms. On each arm is operated one Microchannel Plate detector (MCP) for the collection of the FFs start time and up to 32 Passive Implanted Planar Silicon (PIPS) detectors for the stop time and energy detection of the FFs. However, challenges in the experimental measurements with VERDI arise due to the high degree of ionization (plasma) in the detector material from the interaction with the FFs. The plasma causes a delay in the charge carriers' migration for the signal start, known as the plasma delay time effect (PDT). Furthermore, the recombination of charge carriers in the plasma causes a shrinking in the signal's height, known as pulse height defect (PHD). This phenomenon leads to inaccuracies in the measurement of FFs mass distributions and increased systematic uncertainties.  Previous studies on PDT and PHD have shown varying behaviors across different detector types, which motivated dedicated studies in the type of PIPS detectors used in VERDI. An experimental campaign to characterize the PDT and PHD in PIPS detectors was conducted in the LOHENGRIN recoil separator, which is part of the ILL nuclear facility in Grenoble, France. Measurements of FFs in a range of masses between 80 u and 149 u, with energies between 20 MeV to 110 MeV, were taken to fully characterize six PIPS detectors. The resulting PDT and PHD values were 1 ns to 4 ns and 2 MeV to 10 MeV respectively. The PDT and PHD exhibited consistent energy and mass dependencies across the detectors, which enables the possibility of an event-by-event correction of VERDI data. In this thesis, the basis for discussing the results of the studies of the PDT and PHD effects will be presented.