Robert John Dwayne Miller

Observation of the cascaded atomic-to-global length scales driving protein motion

Model studies of the ligand photodissociation process of carboxymyoglobin have been conducted by using amplified few-cycle laser pulses short enough in duration (<10 fs) to capture the phase of the induced nuclear motions. The reaction-driven modes are observed directly in real time and depict the pathway by which energy liberated in the localized reaction site is efficiently channeled to functionally relevant mesoscale motions of the protein.

Novel composite structure Nd:YAG gain media for high power scaling of side-pumped configurations

We test two novel, side-pumped fused and optically contacted composite Nd:YAG slabs where the laser mode propagates parallel to the layer boundaries. Although these composite rods provide output and beam quality comparable to standard side pumped rods, we measure significant beam distortion near layer boundaries. We show through detailed calculation and experiment that scattering near layer boundaries in these composite structures is mostly due to the small index of refraction difference between Nd:YAG and undoped YAG.

Development of a 25 W TEM00 diode-pumped Nd:YLF laser

Abstract We report the design and the operation of a novel two-head, side-pumped Nd:YLF laser that generates up to 25 W TEM 00 output power at 1.053 μm. The anisotropic thermal lensing of each laser head has been examined and compensated with cylindrical lenses. The output power of this two-head laser exhibits excellent dynamic range with a typical optical–optical conversion efficiency of 18%.

Polarization-dependent spectral modulation in femtosecond Ti:sapphire lasers

We investigate spectral modulation in self-mode-locked femtosecond Ti:sapphire lasers. The spectra of the laser output and of the light reflected from intracavity surfaces can exhibit a periodic modulation due to the laser rod acting as an intracavity birefringent filter. These spectral features vary greatly between the two orthogonally polarized components of the laser beam. The free spectral range and depth of the observed modulation depend on the crystal length and cavity alignment respectively. The qualitative features of the observed spectra can be explained using a simple model of the coupling between polarization states of the laser due to the birefringence of the laser rod.

Chapter 77 - Reaction driven modes in carboxymyoglobin: pathway of force transduction for functionally relevant protein motions

Heme proteins form the cornerstone for our understanding of the general phenomena of molecular cooperativity; where the binding affinity of diatomic ligands in hemoglobin and associated changes in quaternary structure with ligation state is the best-characterized example. At the heart of this problem is an understanding how the initially localized reaction forces couple to the global protein coordinate to execute these functionally relevant motions. The energetics for this process are derived from one or a few chemical bonds and at the instant the bond is formed or broken, the motions are necessarily localized over atomic length scales at the active site and subject to quantum effects. From a practical standpoint, the heme proteins provide ideal model systems for studying the relationship between protein structure and function since they are well-characterized and their ligands can be photo-dissociated with unit quantum efficiency on the truly femtosecond timescale. This chapter discusses the results of ultrafast pump-probe spectroscopy of carboxymyoglobin (MbCO) to determine the initial structure changes of the ligand dissociation process using pulses of less than 10 fs in the 500-600 nm spectral regions.