Nanophotonics & Biofunctional Structures (NPBS)
We use ultra-fast-spectroscopy and advanced microscopy to understand optical energy transduction and quantum sensing, and also create nature-inspired assemblies for energy conversion, transport, and biosensing.
The Nanophotonics and Biofunctional Structures (nPBS) group is focused on understanding and controlling light-matter interactions in nanomaterials. Our approach is to visualize and characterize the dynamics of light-induced processes through time-resolved spectroscopies and microscopies that are designed to operate over multiple contrast mechanisms and energy ranges, so as to gain a complete view and develop predictive power regarding energy flow, conversion, and dissipation within nanostructures and to the surrounding environment. Principles of bio-assembly, synthesis, and nanofabrication are used to design and precisely construct optical and bioinspired nanomaterials to be studied. Through this approach, we ultimately seek to discover novel optical nanomaterials and phenomena that can impact technologically important areas.
Our work spans numerous key needs of importance to our research themes. Among these, in quantum information science we target the development of nanoscale single-photon sources for quantum optics and achievement of critical improvements in their deterministic placement. We are further pursuing photon entanglement and the development of new approaches to transduction of quantum information in hybrid quantum systems. Our nanomaterial synthesis and bioassembly approaches are used to enable new opportunities in optical biosensing, energy transport, and energy conversion. We seek also to understand ultrafast processes in nanomaterials that influence functionality, such as the dynamics of hot carriers in nanostructures, the role of interfaces, the influence of phonon flow on optical energy conversion, and the dynamics of exciton transport in bio-assemblies. We characterize the dynamics of charge, exciton, and spin transport in new interacting nanoparticle assemblies with tunable electronic states and coherences.
Research activities in nPBS include:
- Hybrid systems—to build new forms of matter with tailored functionalities
- Visualization of nanoparticle interactions—to understand, predict, and design physical and chemical interactions
- Quantum information science research, including studies of photon correlation and entanglement, coherent excitations, and quantum transduction
- Evolution of nanostructures under external stimuli—in situ and in operando studies to understand dynamic mechanisms
- Ultrafast transient absorption and emission spectroscopies and microscopies to understand energy flow, light harvesting, and charge separation in nanoscale systems
- Creating new nanoscale functionalities for nanophotonics, quantum sensing, and energy conversion
Key Capabilities
- Femtosecond to microsecond time-resolved absorption spectroscopy with UV to NIR excitation and UV to THz probe
- Ultrafast photoluminescence spectroscopy and microscopy from UV through NIR
- Single-photon microscope for quantum optics and photon correlation studies
- Confocal Raman microscopy and mapping
- Pulsed and continuous-wave electron paramagnetic resonance
- Scanning electron microscopy and laser scanning confocal fluorescence microscopy
- Synthesis of nanoparticles, clusters, and bio-hybrid nanoparticles
- Nanoparticle self-assembly
- Automated synthesizers for synthesis of DNA, RNA, and peptides
- Automated, high-throughput materials synthesis, processing, and characterization
Group capabilities
General
Agilent 1260 Infinity II High Temperature GPC
Agilent 1260 Infinity II High Temperature GPC is for characterizing polymer molecular weight.
Scientific Contact: Jie Xu
TCSPC Microscopy (400-800 nm)
Visible and Near-IR Microscope. This is an inverted microscope-based spectroscopy system with a 300 mm triple-grating spectrograph and dual (visible and short-wave near-IR) 2D array detectors. The visible CCD detector (1360 x 100 pixels) covers 300 to 1000 nm and a thermoelectrically cooled InGaAs detector (640 x 512 pixels) covers 800 to 1650 nm. The system is capable of performing absorption/reflection spectroscopy, photoluminescence spectroscopy (excitation provided by continuous wave and pulsed diode lasers), and visible photoluminescence lifetime measurements. Additionally, the system is equipped with source meters that enable electroluminescence measurements on nanoscale materials incorporated into transistor structures. A microscopy cryostat is available for measurements to 5K.
THz probe
The lab is equipped with an amplified Ti:sapphire laser system capable of 40-fs and an optical parametric amplifier (OPA). Currently, the primary use of the system is for static and time-resolved THz absorption measurements.
Time-correlated single photon counting (TCSPC) spectroscopy (Photon-correlation microscope))
Visible and Near-IR Microscope. This is an inverted microscope-based spectroscopy system with a 300 mm triple-grating spectrograph and dual (visible and short-wave near-IR) 2D array detectors. The visible CCD detector (1360 x 100 pixels) covers 300 to 1000 nm and a thermoelectrically cooled InGaAs detector (640 x 512 pixels) covers 800 to 1650 nm. The system is capable of performing absorption/reflection spectroscopy, photoluminescence spectroscopy (excitation provided by continuous wave and pulsed diode lasers), and visible photoluminescence lifetime measurements. Additionally, the system is equipped with source meters that enable electroluminescence measurements on nanoscale materials incorporated into transistor structures. A microscopy cryostat is available for measurements to 5K.
Visible and near-IR TCSPC with streak camera
Two-Color NIR Transient Absorption and Emission Spectrometer is built off of an amplified Newport Spectra-Physics amplified femtosecond laser system. It is equipped with two OPAs, one operational in the visible and NIR, and the other in the NIR to IR regions. Requests for semiconductor quantum dots (QD) and nanotube photophysics require probe wavelengths beyond 1400 nm. The system is also equipped with a Hamamatsu C5680 streak camera system with 2-ps temporal resolution, and a closed-cycle liquid He cryostat.
Characterization
Bench-top spectroscopy
Stand alone spectrometers are available that enable UV-vis absorption, infrared absorption, circular dichroism, and photoluminescence are available.
Correlation/antibunching measurements
g(2) photon correlation measurements can be performed with a variety of laser excitation sources. Detection can be performed in the visible or near-infrared spectral ranges.
Electron Paramagnetic Resonance EPR EleXsys 500-E (CW)
Bruker EleXsys 500-E EPR Spectrometer is equipped for continuous wave X-band spectroscopy, a light-accessible cavity, and accommodates variable temperatures. The magnetic field operates at up to 1.5 Tesla.
Scientific Contact: H. Christopher Fry
enVISion Transient Absorption Spectrometer
Transient absorption spectrometer with 100 ns to 4 ms timespan and 355 nm excitation.
Scientific Contact: H. Christopher Fry
FLS1000 spectrofluorimeter
Edinburgh Instruments FLS-1000 spectrofluorimeter for steady state and time-resolved photoluminescence measurements. Excitation range: 250 nm – 1200 nm. Emission range: 250 nm – 1700 nm.
Scientific Contact: David Gosztola
GC-MS (Agilent 5975C Series GC/MSD)
This custom-built Agilent 5975C Series GC/ GC-MSD system has flexible carrier gas plumbing, electron impact ionization, TCD and an Agilent MSD Productivity ChemStation. It includes manual or sequence auto sampling as well as a headspace sampling module for analysis of heterogeneous, aqueous and environmental samples. Applications include but are not limited to: organic molecule structure analysis, gas analysis (e.g. H2, N2, CO, CO2), catalysis, and environmental sampling. A tunable photochemistry set-up, a fume hood and standard gas mixtures also are available.
Scientific Contact: Elena Rozhkova
HPLC (Agilent 1260 LC System)
This liquid chromatography (LC) system is capable of analyzing or purifying molecular compounds in either reversed phase (e.g. for peptides) or normal phase (e.g. for small molecules or polymers). The system is equipped with a 100 position autosampler, multiwavelength detector, and automated fraction collector. In addition, mass spectrometry (MS) detection is made possible by the addition of the Advion Expression CMS to enable LC-MS methods.
Scientific Contact: H. Christopher Fry
Magneto-optical Microscope
The magneto-optical microscope is comprised of a confocal laser microscope coupled to a 9 T superconducting magnet. It is equipped with cryostats for cryogenic temperature experiments. The setup is also installed with both continuous-wave and femtosecond pulsed lasers covering wavelengths from 370 nm to 1300 nm, as well as visible and near-infrared cameras and photon-counting detectors for imaging, static and time-resolved spectroscopic studies under external magnetic fields. A Rohde & Schwarz SMA100B RF and Microwave Signal Generator and ZNB Analyzer was added in 2020 (SSB phase noise f = 10 GHz; offset frequency = 10 kHz; 1 Hz measurement bandwidth; < -128 dBc. The ZNB analyzers feature high measurement speed, outstanding precision and exceptional ease of operation. Frequency range from 9 kHz up to 40 GHz Wide dynamic range of up to 140 dB Short sweep times, e.g. 4 ms for 401 points High temperature stability of typ. 0.01 dB/°C). This is a custom-built instrument with components from various vendors built over the span from 2018-2020.
Scientific Contact: David Gosztola
MEOS: Magneto-Electro-Optical Spectrometer
Magneto-Electro-Optical Spectroscopy (MEOS). This is a comprehensive measurement suite that can characterize electrical, magnetic and optical properties of nanodevices or materials. It is equipped with two continuously tunable external-cavity lasers: one in the telecom C band (1520-1570nm), and the other in the 765-780nm band, all with sub-picometer resolutions. It also microwave vector network analyzers that goes up to 20 GHz, and an electromagnet that can provide magnetic field up to 1 T. All the characterizations can be coherent, and multiple different characterizations can be simultaneously carried out. With all these capabilities combined, this tool is suitable for applications such as electro-/magneto-optical characterization, microwave-optical conversion, etc.
Scientific Contact: David Gosztola
Pulsed Electron Paramagnetic Resonance EPR EleXsys-II 580
VT X-BAND PULSED ELECTRON PARAMAGNETIC RESONANCE (EPR) WITH LIGHT EXCITATION CAPABILITY. Pulsed EPR techniques enable controllable manipulation of electron spins and spin dynamics in the nanosecond time regime. With a wide variety of pulse sequences, the Bruker ELEXSYS-II 580 X-band EPR spectrometer allows one to ascertain extensive knowledge about structural properties surrounding probed spins as well as their mutual interactions. Coupled with light excitation, pulsed EPR gives unprecedented control of the excited states, their spin populations, and the mechanisms of their interaction with the environment. This variable temperature system provides detection resolution of 1 nanosecond and excitation and detection of signals up to 1 GHz. This allows for the study of quantum phenomena in crystalline and optically active media.
Operational modes include:
ESSED: Echo Saturation and Stimulated Echo Decay
ESEEM: Electron Spin Echo and Envelope Modulation
HYSCORE: Hyperfine Sub-level Correlation Spectroscopy
ENDOR: Electron Nuclear Double Resonance
DEER/PELDOR: Double Electron-Electron Resonance/Pulsed Electron Double Resonance
SECSY: Spin Echo Correlation Spectroscopy
EXSY: Exchange Spectroscopy
Scientific Contact: H. Christopher Fry
Raman spectroscopy
Raman spectroscopy and spatial mapping are available with laser sources spanning ultraviolet thru near-infrared.
Scientific Contact: David Gosztola
Time-resolved emission spectroscopy (streak camera)
This lab is equipped with an amplified Ti:sapphire laser system capable of 40-fs and an optical parametric amplifier (OPA). A few-picosecond time-resolution, single-photon sensitive streak camera with response from ~250-900nm for time-resolved photoluminescence measurements.
Transient absorption spectroscopy
This lab is equipped with a 5kHz amplified Ti:sapphire laser system capable of 80-fs and an optical parametric amplifier (OPA). Currently, the primary use of the system is for time-resolved absorption out to ~2.5ns with ultraviolet, visible, or near-infrared probing.
Visible and near-IR microscopy
Visible and Near-IR Microscope. This is an inverted microscope-based spectroscopy system with a 300 mm triple-grating spectrograph and dual (visible and short-wave near-IR) 2D array detectors. The visible CCD detector (1360 x 100 pixels) covers 300 to 1000 nm and a thermoelectrically cooled InGaAs detector (640 x 512 pixels) covers 800 to 1650 nm. The system is capable of performing absorption/reflection spectroscopy, photoluminescence spectroscopy (excitation provided by continuous wave and pulsed diode lasers), and visible photoluminescence lifetime measurements. Additionally, the system is equipped with source meters that enable electroluminescence measurements on nanoscale materials incorporated into transistor structures. A microscopy cryostat is available for measurements to 5K.
ZetaSizer Nano, Malvern (particle size potential)
The Malvern Zetasizer Nano ZS measures the size (dynamic light scattering) and electrokinetic potential (phase analysis light scattering) of proteins, colloids, and nanoparticles from 0.3 nm to 10 um. For measurements in organic solvents, a dip cell is available.
Scientific Contact: H. Christopher Fry
Imaging
Field Emission Scanning Electron Microscope, JEOL JSM-7500F
JEOL 7500 Field-emission Scanning Electron Microscope provides high-resolution imaging utilizing backscattered or secondary electrons for nanometer-scale inspection. The microscope is capable of handling samples of various sizes, from small pieces to 150-mm-diameter wafers, and includes secondary and backscattered electron imaging capabilities, energy-dispersive X-ray fluorescence spectroscopy, and a transmitted electron detector. Image resolution using secondary electrons is less than 1 nm at 15 kV and less than 1.5 nm at 1 kV.
Scientific Contact: Elena Shevchenko
Synthesis/Sample Prep
Automated Thin Film Solution Processing Robot
Establish the process for the safe and effective conduct of automated solution-shearing thin films. The purpose of the solution-shearing is to produce layers of material, typically polymers, on flat substrates. This procedure addresses the actions required for solution handling, preparation of substrates, automated equipment setup, the shearing itself, and the final cleanup.
Scientific Contact: Jie Xu
Peptide Synthesizer
The AAPPTEC Apex 396 automated peptide synthesizer is capable of synthesizing 1-96 peptides in parallel. The tool is useful in synthesizing peptide libraries that can be screened for various materials properties. In addition to peptides, peptoids (a sequence controlled polymer system analogous to peptides) have been synthesized on this tool.
Scientific Contact: H. Christopher Fry
Solution-Shearing Station
The purpose of the solution-shearing station is to produce layers of materials on flat substrate by shearing blade.
Scientific Contact: Jie Xu
Synthesis
Synthesis capabilities in surface modification of nanoparticles, functionalization, quantum dots, metal nanoparticles, and metal oxide nanoparticles.
Thin film transfer system
This thin material transfer system consists of three stacked transfer stages coupled to an optical microscope. The stacked stages allow 3D motions of the samples. A temperature control unit is also installed for heating samples.
Scientific Contact: H. Christopher Fry