Browsing Department of Chemistry Faculty Publications by Title
Now showing items 41-60 of 86
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Long-Period Gratings in Chemical Sensing
(2016-03-21)A chemical sensor system consisting of a coated long period grating, which was spliced into a fiber loop cavity, has been prepared and characterized. Designer coatings based on polydimethylsiloxane and nanostructured ... -
Loss Determination in Microsphere Resonators by Phase-Shift Cavity Ring-Down Measurements
(2016-03-21)The optical loss of whispering gallery modes of resonantly excited microresonator spheres is determined by optical lifetime measurements. The phase-shift cavity ring-down technique is used to extract ring-down times and ... -
Measurements of Energy Partitioning in H2 Formation by Photolysis of Amorphous Water Ice
(2016-03-21)We demonstrate experimentally that photodissociation of amorphous solid water at 100 K results in formation of H2 molecules with an ortho/para ratio of gOPR = 3. Two distinct mechanisms can be identified: endothermic ... -
Modeling of Fiber-Optic Fluorescence Probes for Strongly Absorbing Samples
(2016-03-08)The dynamic range of fiber-optic fluorescent probes such as single fibers and fiber bundles is calculated for strongly absorbing samples, such as process liquids, foodstuffs, and lubricants. The model assumes an excitation ... -
Monitoring of Vapor Uptake by Refractive Index and Thickness Measurements in Thin Films
(2016-03-04)We report a method for real-time monitoring of vapor uptake by simultaneous detection of the refractive index, 𝑛 , and thickness, 𝑑 , of thin transparent films with a precision of 𝛿𝑛=10 −4 and 𝛿𝑑<100 nm . The setup ... -
A Multi-Dimensional Smolyak Collocation Method in Curvilinear Coordinates for Computing Vibrational Spectra
(2015-12-02)In this paper, we improve the collocation method for computing vibrational spectra that was presented in Avila and Carrington, Jr. [J. Chem. Phys. 139, 134114 (2013)]. Using an iterative eigensolver, energy levels and ... -
Musical Instrument Pickup Based on a Laser Locked to an Optical Fiber Resonator
(2016-03-11)A low-noise transducer based on a fiber Fabry-Perot (FFP) cavity was used as a pickup for an acoustic guitar. A distributed feedback (DFB) laser was locked to a 25 MHz-wide resonance of the FFP cavity using the Pound-Drever-Hall ... -
Musical Instrument Recordings Made With a Fiber Fabry–Perot Cavity: Photonic Guitar Pickup
(2016-03-17)A 1 cm long, low-finesse fiber-optic cavity was used as a transducer for the vibrations of the soundboard of an acoustic guitar and of a violin. The reflected light is detected and then amplified and recorded using ... -
Near Infrared Absorption Detection in Picolitre Liquid Volumes Using Fiber Loop Ring-Down Detection
(2016-03-07)Cavity ring-down spectroscopy is performed using a single-mode fibre loop as an optical cavity. The loop contains absorption cells for either liquids or gases, as well as an erbium-doped fibre amplifier. The fibre amplifier ... -
Neural Networks vs Gaussian Process Regression for Representing Potential Energy Surfaces: a Comparative Study of Fit Quality and Vibrational Spectrum Accuracy
(2018)For molecules with more than three atoms, it is difficult to fit or interpolate a potential energy surface (PES) from a small number of (usually ab initio) energies at points. Many methods have been proposed in recent ... -
A New Collocation-Based Multi-Configuration Time-Dependent Hartree (MCTDH) Approach for Solving the Schrödinger Equation With a General Potential Energy Surface
(2018-01-08)We present a new collocation-based multi-configuration time-dependent Hartree (MCTDH) approach for solving the Schrödinger equation required to compute (ro-)vibrational spectra, photodissociation cross sections, reaction ... -
Optical Fiber Sensing Based on Reflection Laser Spectroscopy
(2016-03-22)An overview on high-resolution and fast interrogation of optical-fiber sensors relying on laser reflection spectroscopy is given. Fiber Bragg-gratings (FBGs) and FBG resonators built in fibers of different types are used ... -
Perspective: Computing (ro-)Vibrational Spectra of Molecules With More Than Four Atoms
(2017-03-31)In this perspective, I review methods for computing (ro-)vibrational energy levels and wavefunctions of molecules with more than four atoms. I identify three problems one confronts (1) reducing the size of the basis; (2) ... -
Phase-Shift Cavity Ring-Down Spectroscopy on a Microsphere Resonator by Rayleigh Backscattering
(2016-03-04)The optical ring-down time in a silica microsphere resonator is measured using phase-shift cavity ring-down spectroscopy. When detecting Rayleigh backscattered light that is coupled into the input waveguide it is found ... -
Photoelectron Imaging Following 2 þ 1 Multiphoton Excitation of HBr
(2016-03-29)The photodissociation and photoionization dynamics of HBr via low-n Rydberg and ion-pair states was studied by using 2 + 1 REMPI spectroscopy and velocity map imaging of photoelectrons. Two-photon excitation at about 9.4–10 ... -
Photonic Guitar Pick-up: Fiber Strain Sensors Find Applications in Music Recording
(2016-03-07)In this report we give a summary of our work on the development of low-noise fiber-optic strain sensors. Three types of strain sensors were developed and were tested by attaching them to the bodies of acoustic guitars. The ... -
Proton Formation in 2+1 Resonance Enhanced Multiphoton Excitation of HCl and HBr via „=0… Rydberg and Ion-Pair States
(2016-03-22)Molecular beam cooled HCl was state selected by two-photon excitation of the V (1) summation operator(0(+)) [v=9,11-13,15], E (1) summation operator(0(+)) [v=0], and g (3) summation operator(-)(0(+)) [v=0] states through ... -
A Pruned Collocation-Based Multiconfiguration Time-Dependent Hartree Approach Using a Smolyak Grid for Solving the Schrödinger Equation with a General Potential Energy Surface
(2019)Standard multiconfiguration time-dependent Hartree (MCTDH) calculations use a direct product basis and rely on the potential being a sum of products (SOPs). The size of the direct product MCTDH basis scales exponentially ... -
Purification and Kinetic Characterization of the Essential Condensation Enzymes Involved in Prodiginine and Tambjamine Biosynthesis
(Wiley, 2019)Prodiginines and tambjamines are related families of bioactive alkaloid natural products with pharmaceutical potential. Both compound families result from a convergent biosynthetic pathway ending in the condensation of a ... -
Quantification of Different Water Species in Acetone using a NIR-Triple-Wavelength Fiber Laser
(2016-02-25)A fiber laser using a thulium-doped ZBLAN gain medium was used to generate laser radiation simultaneously at 1461, 1505 and 1874 nm, with > 5 mW output power at each of the wavelengths. The laser was used to quantify the ...