The effect of low energy irradiation, where the sputtering is imperceptible, has not been deeply studied in the pattern formation. In this work, we want to address this question by analyzing the nanoscale topography formation on Si surface, which is irradiated at room temperature by Ar + ions near the displacement threshold energy, for incidence angles ranging from 0 to 85 •. The transition from smooth to ripple patterned surface, i.e. the stability/instability bifurcation angle is observed at 55 • , whereas the ripples with their wave-vector is parallel to the ion beam projection in the angular window of 60-70 • , and with 90 • rotation with respect to the ion beam projection at the grazing angles of incidence. A similar irradiation setup has been simulated by means of molecular dynamics, which made it possible, firstly, to quantify the effect of the irradiation in terms of erosion and redistribution using sequential irradiation and, secondly, to evaluate the ripple wavelength using the crater function formalism. The ripple formation results can be solely attributed to the mass redistribution based mechanism, as erosion due to ion sputtering near or above the threshold energy is practically negligible.

INTRODUCTION 1 2.0 THEORY DEVELOPMENT 2.1 Light Scattering Theory 2.2 Fluctuations and Time-Correlation Functions 2.3 Photon Correlation Spectroscopy 2.4 Optical Mixing Techniques 2.4.1 Heterodyne Correlation Function 2.4.2 Homodyne Correlation Function 3.0 EXPERIMENTAL APPROACH 3.1 Optical Component Arrangement 3.2 Data Analysis 3.3 Initial Experiment 3.4 Final Experiment 4.0 DISCUSSION AND CONCLUSION REFERENCES LIST OF FIGURES Figure Pa g e 3.1.1 Optical Table 35 3.1.2 Photomultiplier tube housing 3.1.3 Data acquisition system 3.3.1 Inverse correlation time versus Sin 9/2 for a non-flowing system 3.3.2 Initial experimental set up 3.3.3 A typical plot showing polydispersity 3.3.4 A typical plot showing multiple scattering 3.3.5 Y-intercept of the SI plot versus flow rate for 10 m.m. I.D. tube using initial set up 3.3.6 Y-intercept of the SI plot versus flow rate for 6 m.m. I.D. tube using initial set up Revised set up Y-intercept of the SI plot versus flow rate for particles of two different sizes x. and T" versus flow rate for particle of nominal diameters 0.234 p t and T" versus flow rate for particles of nominal diameter 0.091 u Slope of the SI plot versus flow rate squared for particles of two different sizes Slope of the SI plot versus flow rate squared for three converging lenses of different focal lengths 85 4.6 Beam profile 89 4.7 Y-intercept of the SI plot versus flow rate for highly perturbed flow 91 3. 3. 7

Nanofabrication of flat optic silica gratings conformally layered with two-dimensional (2D) MoS 2 is demonstrated over large area (cm 2 ), achieving a strong amplification of the photon absorption in the active 2D layer. The anisotropic subwavelength silica gratings induce a highly ordered periodic modulation of the MoS 2 layer, promoting the excitation of Guided Mode Anomalies (GMA) at the interfaces of the 2D layer. We show the capability to achieve a broadband tuning of these lattice modes from the visible (VIS) to the near-infrared (NIR) by simply tailoring the illumination conditions and/or the period of the lattice. Remarkably, we demonstrate the possibility to strongly confine resonant and nonresonant light into the 2D MoS 2 layers via GMA excitation, leading to a strong absorption enhancement as high as 240% relative to a flat continuous MoS 2 film. Due to their broadband and tunable photon harvesting capabilities, these large area 2D MoS 2 metastructures represent an ideal scalable platform for new generation devices in nanophotonics, photo- detection and -conversion, and quantum technologies.

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Hydrogenated diamond-like carbon (HDLC) has an atomically smooth surface that can be deposited on high-surface area substrata and functionalized with reactive chemical groups, providing an ideal substrate for protein immobilization. A synthetic sequence is described involving deposition and hydrogenation of DLC followed by chemical functionalization. These functional groups are reacted with amines on proteins causing covalent immobilization on contact. Raman measurements confirm the presence of these surface functional groups, and Fourier transform infrared spectroscopy (FTIR) confirms covalent protein immobilization. Atomic force microscopy (AFM) of immobilized proteins is reproducible because proteins do not move as a result of interactions with the AFM probe-tip, thus providing an advantage over mica substrata typically used in AFM studies of protein. HDLC offers many of the same technical advantages as oxidized graphene but also allows for coating large surface areas of biomaterials relevant to the fabrication of medical/biosensor devices.