High-Resolution Nanoscale Solid-State Nuclear Magnetic Resonance Spectroscopy

We present a new method for high-resolution nanoscale magnetic resonance imaging (nano-MRI) that combines the high spin sensitivity of nanowire-based magnetic resonance detection with high spectral resolution nuclear magnetic resonance (NMR) spectroscopy. By applying NMR pulses designed using optimal control theory, we demonstrate a factor of $500$ reduction of the proton spin resonance linewidth in a $(50\text{-nm})^{\text{3}}$ volume of polystyrene and image proton spins in one dimension with a spatial resolution below $2~\text{nm}$.Comment: Main text: 8 pages, 6 figures; supplementary information: 10 pages, 10 figure

Generalized Ellipsometry on Sculptured Thin Films made by Glancing Angle Deposition

In this thesis, physical properties of highly optically and magnetically anisotropic metal sculptured thin films made by glancing angle deposition are presented. Predominantly, the determination of optical and magneto-optical properties with spectroscopic generalized Mueller matrix ellipsometry and homogenization approaches is discussed. Nomenclatures are proposed to unambiguously identify the sculptured thin film geometry. Generalized ellipsometry, a non-destructive optical characterization technique, is employed to determine geometrical structure and anisotropic dielectric properties of highly spatially coherent three-dimensionally nanostructured thin films in the spectral range from 400 to 1700 nm. The analysis of metal slanted columnar thin films (F1-STFs) deposited at glancing angle (θi = 85°) revealed monoclinic optical properties of such nanostructures, and the optical response can be modeled with a single homogeneous biaxial layer. This homogeneous biaxial layer approach is universally applicable to F1-STFs and effective optical properties of the nanostructured thin films are attained. More complex sculptured thin films, which can be engineered by a dynamic in-situ substrate rotation, may be considered as cascaded F1-STFs. A piecewise homogeneous biaxial layer approach is described, which allows for the determination of principal optical constants of chiral multi-fold and helical sculptured thin films. For optical analysis, complex sculptured thin films can be virtually separated into their F1-STF building blocks. It is confirmed that such sculptured thin films have modular optical properties. This characteristic can be exploited to predict the optical response of sculptured thin films grown with arbitrary sequential substrate rotations. Magneto-optical generalized ellipsometry in the polar and longitudinal Kerr geometry is utilized to determine the spectral magneto-optical response of Co F1-STFs and estimate the magnetization direction. Kerr effect measurements and calculations reveal a strong azimuthal dependence with peak Kerr rotation one order of magnitude larger than what has been reported for solid Co thin films. The concept of generalized ellipsometry in conjunction with a three-dimensional vector magnet is introduced and first measurement results presented

Nature’s Optics and Our Understanding of Light

Optical phenomena visible to everyone abundantly illustrate important ideas in science and mathematics. The phenomena considered include rainbows, sparkling reflections on water, green flashes, earthlight on the moon, glories, daylight, crystals, and the squint moon. The concepts include refraction, wave interference, numerical experiments, asymptotics, Regge poles, polarisation singularities, conical intersections, and visual illusions

Generalized Ellipsometry on Sculptured Thin Films made by Glancing Angle Deposition

In this thesis, physical properties of highly optically and magnetically anisotropic metal sculptured thin films made by glancing angle deposition are presented. Predominantly, the determination of optical and magneto-optical properties with spectroscopic generalized Mueller matrix ellipsometry and homogenization approaches is discussed. Nomenclatures are proposed to unambiguously identify the sculptured thin film geometry. Generalized ellipsometry, a non-destructive optical characterization technique, is employed to determine geometrical structure and anisotropic dielectric properties of highly spatially coherent three-dimensionally nanostructured thin films in the spectral range from 400 to 1700 nm. The analysis of metal slanted columnar thin films (F1-STFs) deposited at glancing angle (θi = 85°) revealed monoclinic optical properties of such nanostructures, and the optical response can be modeled with a single homogeneous biaxial layer. This homogeneous biaxial layer approach is universally applicable to F1-STFs and effective optical properties of the nanostructured thin films are attained. More complex sculptured thin films, which can be engineered by a dynamic in-situ substrate rotation, may be considered as cascaded F1-STFs. A piecewise homogeneous biaxial layer approach is described, which allows for the determination of principal optical constants of chiral multi-fold and helical sculptured thin films. For optical analysis, complex sculptured thin films can be virtually separated into their F1-STF building blocks. It is confirmed that such sculptured thin films have modular optical properties. This characteristic can be exploited to predict the optical response of sculptured thin films grown with arbitrary sequential substrate rotations. Magneto-optical generalized ellipsometry in the polar and longitudinal Kerr geometry is utilized to determine the spectral magneto-optical response of Co F1-STFs and estimate the magnetization direction. Kerr effect measurements and calculations reveal a strong azimuthal dependence with peak Kerr rotation one order of magnitude larger than what has been reported for solid Co thin films. The concept of generalized ellipsometry in conjunction with a three-dimensional vector magnet is introduced and first measurement results presented

Lasing of whispering gallery modes in optofluidic microcapillaries

Abstract not availableAlexandre François, Nicolas Riesen, Kirsty Gardner, Tanya M. Monro, and Al Meldru

Flexographic printed nanogranular LBZA derived ZnO gas sensors: Synthesis, printing and processing

Within this document, investigations of the processes towards the production of a flexographic printed ZnO gas sensor for breath H2 analysis are presented. Initially, a hexamethylenetetramine (HMTA) based, microwave assisted, synthesis method of layered basic zinc acetate (LBZA) nanomaterials was investigated. Using the synthesised LBZA, a dropcast nanogranular ZnO gas sensor was produced. The testing of the sensor showed high sensitivity towards hydrogen with response (Resistanceair/ Resistancegas) to 200 ppm H2 at 328 °C of 7.27. The sensor is highly competitive with non-catalyst surface decorated sensors and sensitive enough to measure current H2 guideline thresholds for carbohydrate malabsorption (Positive test threshold: 20 ppm H2, Predicted response: 1.34). Secondly, a novel LBZA synthesis method was developed, replacing the HMTA by NaOH. This resulted in a large yield improvement, from a [OH-] conversion of 4.08 at% to 71.2 at%. The effects of [OH-]/[Zn2+] ratio, microwave exposure and transport to nucleation rate ratio on purity, length, aspect ratio and polydispersity were investigated in detail. Using classical nucleation theory, analysis of the basal layer charge symmetries, and oriented attachment theory, a dipole-oriented attachment reaction mechanism is presented. The mechanism is the first theory in literature capable of describing all observed morphological features along length scales. The importance of transport to nucleation rate ratio as the defining property that controls purity and polydispersity is then shown. Using the NaOH derived LBZA, a flexographic printing ink was developed, and proof-of-concept sensors printed. Gas sensing results showed a high response to 200 ppm H2 at 300 °C of 60.2. Through IV measurements and SEM analysis this was shown to be a result of transfer of silver between the electrode and the sensing layer during the printing process. Finally, Investigations into the intense pulsed light treatment of LBZA were conducted. The results show that dehydration at 150 °C prior to exposure is a requirement for successful calcination, producing ZnO quantum dots (QDs) in the process. SEM measurements show mean radii of 1.77-2.02 nm. The QDs show size confinement effects with the exciton blue shifting by 0.105 eV, and exceptionally low defect emission in photoluminescence spectra, indicative of high crystalline quality, and high conductivity. Due to the high crystalline quality and amenity to printing, the IPL ZnO QDs have numerous potential uses ranging from sensing to opto-electronic devices

Influence of varying analyte concentration, environment, and composition on nanoshell-based SERS

This thesis describes a series of experiments designed to examine the use of Au nanoshells as highly controllable surface enhanced Raman spectroscopy (SERS) nanosensor substrates. Individual Au nanoshells provide simple, scalable substrates for SERS with demonstrated strong electromagnetic field enhancements which exist near the molecule-substrate interface. The SERS spectral response is explored as a function of analyte concentration, environmental pH, and various analyte properties and composition. As a function of analyte concentration, the SERS response is exploited for the determination of packing density and molecular conformation of thiolated poly(ethylene glycol) (PEG) adsorbates on Au nanoshells. By varying the environmental pH when a pH-sensitive molecular adsorbate is attached to the Au nanoshells, the resultant SERS spectra allow for local pH monitoring with an average accuracy of +/-0.10 pH units across the operating range of the nanodevice. Changing analyte properties, such as carbon chain length for alkanethiol self-assembled monolayers (SAMs) on gold, produces a series of sharp resonances in the SERS spectra, suggesting coupling of the gold-sulfur bond stretch with the longitudinal acoustic, "accordion", vibrations of the molecular alkane chain. Further variation in chain termination or the addition of a phospholipid headgroup yields observable SERS spectral differences, providing unique fingerprints for each molecule. An associated phospholipid layer assembled onto an underlying alkanethiol SAM forms a hybrid bilayer on Au nanoshells, providing a way to spectrally monitor intercalation of the nonsteroidal anti-inflammatory drug (NSAID), ibuprofen. Low frequency SERS peaks for halogen, nitrogen, and oxygen containing molecules act as probes for metal-adsorbate binding, with spectral evidence for carbon monoxide adsorption occurring in the high frequency region. Finally, we demonstrate the synthesis and characterization of nanoparticles composed of magnetic cores with continuous Au shell layers that simultaneously possess both magnetic and plasmonic properties. The work presented in this thesis further demonstrates the emergence of Au nanoshells as versatile and valuable tools for sensing applications