Nano-ESI mass spectrometry is an attractive analytical technique due to its high sensitivity and small sample consumption, which is especially important for research areas such as proteomics. However, current nano-ESI emitters become a bottleneck for nano-ESI to be widely applied because of problems such as clogging, poor robustness, large flow resistance, and poor spray efficiency for highly aqueous solutions. The objective of this thesis study is to address the problems associated with tapered emitters and provide alternative solutions by developing advanced nano-ESI emitters. Two strategies that were explored to improve the clogging resistance and robustness while maintaining comparable electrospray performances include the development of emitters with larger apertures and multiple channels. Following these strategies, five types of emitters were fabricated without tapering either internal or external diameters, which include a roughened open tubular emitter, a porous membrane-assisted emitter, a microstructured multiple channel photonic crystal fiber (MSF) emitter, a packed ODS bead emitter, and an entrapped ODS bead emitter. The successful transformation of MSF fibers to nanoelectrospray emitters demonstrates a new practical approach to expand the application of nano-ESI because of its availability, compatibility, precisely controlled channel dimensions, variety of channel patterns, and feasibility for surface modification. The fundamental mechanism of non-tapered emitters was studied at nano flow rates. The fact that a plume of mist, instead of single Taylor cone, is generated from multiple channel emitters at nano flow rates suggests multiple Taylor cones may be formed. The calculated sensitivity gains from a MSF emitter compared to a single-tip tapered emitter are related to the number of the orifices containing on a MSF emitter. The characterization of impacts of operational parameters on nanoelectrospray performances shows that non-tapered emitters are more robust and less dependent on the emitter’s fine positioning. It was also found that unlike tapered emitters, non-tapered emitters can be positioned ten times further from the orifice of a mass spectrometer, which is greatly beneficial to online sample manipulation and purification. Furthermore, the electrospray efficiency of spraying highly aqueous solutions (e.g. 90%) was greatly improved through the hydrophobic modification of a MSF emitter exit. / Thesis (Ph.D, Chemistry) -- Queen's University, 2008-09-17 19:07:12.847

This thesis reports the design, fabrication, and operation of silicone based multiplexed electrospray (MES) emitters. After reviewing the feasibility of utilizing electrospray as a scalable thin film deposition technique as well as the advantages and limitations of prior MES emitters, we present a design rationale for MES suitable for highly conductive and corrosive fluids. Then we customized a 1064nm fiber laser micromachining system to precisely and rapidly machine silicone sheet and silicon wafers. Laser energy and path are judicially chosen to create clean and round micro posts that form the external structure of the nozzles. For MES with low flow rate per nozzle, it is of vital importance to evenly distribute the liquid into each nozzle on the entire MES array by controlling the pressure drop inside each fluid flow channel. To this end, we modeled the dimension of microfluidic channels that introduce flow impedance overwhelming surface tension at the nozzle tip. We presented laser microfabrication techniques for fabricating two typical types of microfluidic channels: the through-hole array on conductive silicone sheets and the in-plane microfluidic channel on silicon wafers. Next, we developed a convenient assemble process for the integration of three layers (distributor layer, extractor layer, and collector layer) of the MES emitter. The uniformity of the flow rate among nozzles on MES emitters was investigated by observing the overall spray profiles and measuring the diameter of each jet. The results suggest that the silicone-based MES emitters are feasible for spraying highly conductive and corrosive liquids. The MES emitter developed in this thesis may become a promising tool in the scalable manufacturing of thin film perovskite solar cells. / Master of Science

High power, broadband light sources emitting in the 2-2.5 um wavelength range important for optical sensing of important biomolecules in aqueous solutions such as glucose. Here we demonstrate and analyze superluminescent diodes with output centered at 2.4 ums (range ~2.2-2.5 ums) from GaInAsSb/AlGaAsSb quantum wells in a separate confinement structure. Quasi-continuous wave output of 1 mW is achieved at room temperature for 40m x 2mm devices. Superluminescence is evidenced in superlinear growth, spectral narrowing, and angular narrowing of light output with increasing current injection. The output is analyzed and modeled with semiconductor rate equations, and by varying parameters, potential routes for future improvements are explored, such as additional Auger suppression and photonic mode engineering.

Subsurface drip distribution is an important on-site wastewater treatment technique which is widely used with various soil types and restricted site conditions. It can distribute pretreated wastewater uniformly into soil. Some recent field applications showed low application uniformities, which was reflected in overloading of the field near the supply manifold while low emitter discharge rates occurred at the end of lateral. Designers are seeking appropriate operation pressures and drip zone configurations to improve system application uniformity. This research was conducted to test some popular wastewater drip products in both lab and field-scale experiments. The first goal of this study was to evaluate the performance of five subsurface drip products under eight operational pressures ranging from 0 to 310 kPa (45 psi). After evaluation of each group of 60 emitters, results showed that Netafim Bioline pressure compensating (PC) emitters exhibited a uniformity coefficient (UC) of 95% with a coefficient of variance (Cv) of 4.9%. The average UC of Geoflow Wasteflow products is 94.4% and Cv value is 6.8%. Flow rate and pressure relationships (Q-H curves) were developed for each drip emitter tested. By analyzing low and normal operational pressure ranges, Q-H curves were fitted to the data and resulted in R2 values ranging from 1.000 to 0.414. Geoflow pressure compensating products possess the features of non-pressure compensating emitters under low pressure head. Netafim PC products are characterized as pressure compensating over the full range of operational pressures and emit water with nominal uniformity during low pressure range. To evaluate drip zone configurations with respect to distribution uniformity, a field-scale experiment was set up and three drip tubing products were tested in different dosing and operation schemes. Three factors of wastewater drip system design were tested. System operation pressure (138 kPa/20 psi and 276 kPa/40 psi); different pressure control components (pressure regulator/recirculation valve) and schemes (continuous flushing/intermittent flushing); and supply line length (7.6 m/25 ft, 15.2 m/50 ft, and 30.4 m/100 ft) were evaluated to compare their influence on water application uniformity. It was concluded that, for Geoflow PC and NPC products, among all three factors, system operational pressure has the greatest effect on drip system application uniformity; supply line length has the least influence. For Netafim PC tubing, pressure control scheme has the greatest effect on drip system application uniformity; supply line length has the least influence. The optimal combination of the three factors could save more than 10 minutes of dosing time to meet the required dosing application uniformity. An engineering computation example on system fill time was presented and compared to experimental results to demonstrate the possible gap between typical design processes and real field application.

The purpose of this investigation was to determine the parameters of emitter drift and to suggest a mechanism for this phenomenon.

This thesis presents a route towards a single photon source based on erbium-doped nanocrystals, fabricated with methods that use double nanohole optical tweezers. Single photon sources are an exciting quantum technology and erbium is good candidate as it emits in the low-loss fiber optic C-band, but it is a weak emitter. Double nanohole apertures can be designed with plasmonic resonances to enhance the local electric field. In this thesis, double nanohole optical tweezers are used to isolate and enhance the emission of erbium-doped nanocrystals, with the tuned geometry showing a factor of 50 additional enhancement over rectangular apertures. With the enhanced emission, nanocrystals with discrete levels of erbium emitters are detected and isolated in real-time, based on their level of emission. This real-time process demonstrates a major improvement over typical post-processing approaches. A novel method to anchor nanocrystals in a double nanohole using a photochemical thiol reaction was investigated which yielded 40% of nanoparticles anchoring within 2 μm of the DNH, with 5% inside. This is useful as otherwise the trapping laser must be maintained to keep the nanocrystal in the trap. Another challenge is coupling to an optical fiber, for which a method to combine trapping and coupling was explored. Colloidal pattern transfer is presented as a low-cost fabrication method for nanoaperture optical fiber tweezers, with fiber-based trapping demonstrated using 40 nm polystyrene nanospheres and hexagonal boron nitride. The preliminary results from these methods show great potential, and with further refinement they may lead towards a method to fabricate a low-cost fiber-coupled single photon source based on erbium-doped nanocrystals. / Graduate

Zugl.: Konstanz, Univ., Diss., 2009

High-energy light was generated from lower-energy photons through an upconversion process using a mixture of a photosensitizer and an emitter. Factors that influence efficiency of the process were studied. Several ruthenium(II) complexes coordinated with bi- and polypyridyl ligands were prepared and used as photosensitizers. Anthracene and its derivatives were used as emitters. In each experiment, the upconversion sample was irradiated with a laser and the emission was monitored. The emission spectra exhibited upconversion (415-513 nm), scattering laser light (514 or 632.8 nm), and phosphorescence (>550 nm). The laser beam was positioned close to the edge of the sample cuvette to avoid a reduction in the upconversion emission caused by self absorption. Increases in laser power, photosensitizer concentration, or emitter concentration increased the upconversion intensity (Iu). Dissolved oxygen caused a minor decrease in Iu. Different photosensitizer and emitter derivatives were tested. Homoleptic ruthenium complexes were more effective photosensitizers with DPA as emitter than their heteroleptic analogues. Upconversion was detected in the [Ru(deab)3](PF6)2 (deab = 4,4'-bis(N,N-diethylamino)-2,2'-bipyridine) and DPA system using helium-neon (632.8 nm) and argon ion (514 nm) lasers, indicating the same process can occur whenever the photosensitizer absorbs the incident radiation. A detailed mechanism is proposed in which an excitation photon is absorbed by a sensitizer to produce an excited triplet state. Energy is transferred from sensitizer to emitter by collision, generating triplet excited emitter. Two emitter triplets annihilate to produce one highly excited singlet. This singlet emits the upconversion photon. The steady-state approximation is used to explore the upconversion and phosphorescence (Ip) intensities. Ip has a first order dependence on laser power, while Iu varies between first and second order. The variable power dependence of Iu occurs because of the competition between triplet-triplet annihilation and other decay pathways. Finally, (Iu/Ip2) is proportional to the second order of DPA concentration. These results generate a better understanding of the upconversion process and they will help to direct the work of others to enhance the efficiency of photonic devices. Practical applications of upconversion, such as the development of better photovoltaic cells, will be aided by the work described herein.

No description available.

The goal of this research was to evaluate the application uniformity of subsurface drip distribution systems and the recovery of emitter flow rates. Emission volume in the field, and laboratory measured flow rates were determined for emitters from three locations. Additionally, the effects of lateral orientation with respect to slope on emitter plugging was evaluated. Two different emitters were tested to evaluate slope effects on emitter plugging (type Y and Z). The emitters were alternately spliced together and installed in an up and down orientation on slopes of 0, 1, 2 and 4% and along the contour on slopes of 1 and 2%. The emitters were covered with soil and underwent a simulated year of dosing cycles, and then flushed with a flushing velocity of 0.6 m/s. Initial flow rates for the two emitter types were 2.38 L/hr with a C.V. of 0.07. There was no significant difference in flow rates among slopes for type Y emitters, but there was a significant difference between the 1% and 2 % contour slopes for type Z emitters. Application uniformity of three different laterals at each site was evaluated. Sections of the lateral from the beginning, middle and end were excavated and emission volumes were recorded for each emitter. Application uniformity of laterals ranged from 48.69 to 9.49%, 83.55 to 72.60%, and 44.41 to 0% for sites A, B, and C, respectively. Mean emitter flow rate was 2.21, 2.24, and 2.56 L/hr for sites A, B, and C, respectively under laboratory conditions. Application uniformity under laboratory conditions ranged from 70.97 to 14.91%, 86.67 to 79.99%, and 85.04 to 0.00% for sites A, B, and C, respectively. A flushing velocity of 0.15 m/s with no chlorination, shock chlorination of 3400 mg/L and flushing velocity of 0.15 m/s, and shock chlorination of 3400 mg/L and flushing velocity of 0.6 m/s treatment regiments were applied to all laterals collected to assess emitter flow rate recovery to the nominal flow rate published by the manufacturer. All laterals showed an increase in the number of emitters within 10% of the published nominal flow rate.