Clark-MXR is Laser Institute of America's Featured Member in July

 

An industry leader in Ultrashort Pulse laser based micromachining and the production of ultrafast lasers and laser-based solutions for scientific research and industrial applications, Clark-MXR, Inc. is known for offering unparalleled contract manufacturing services and easy-to-use laser products at a low cost of ownership.

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Recent publication from KAUST with Model IMPULSE:

Mapping Carrier Dynamics on Material Surfaces in Space and Time using Scanning Ultrafast Electron Microscopy

Jingya Sun, Aniruddha Adhikari, Basamat S. Shaheen, Haoze Yang, and Omar F. Mohammed*
Solar and Photovoltaics Engineering Research Center, Division of Physical Sciences and Engineering, King Abdullah University of Science and Technology, Thuwal 23955-6900, Kingdom of Saudi Arabia

DOI: 10.1021/acs.jpclett.5b02908

ABSTRACT: 

Selectively capturing the ultrafast dynamics of charge carriers on materials surfaces and at interfaces is crucial to the design of solar cells and optoelectronic devices. Despite extensive research efforts over the past few decades, information and understanding about surface-dynamical processes, including carrier trapping and recombination remains extremely limited. A key challenge is to selectively map such dynamic processes, a capability that is hitherto impractical by time-resolved laser techniques, which are limited by the laser’s relatively large penetration depth and consequently these techniques record mainly bulk information. Such surface dynamics can only be mapped in real space and time by applying four-dimensional (4D) scanning ultrafast electron microscopy (S-UEM), which records snapshots of materials surfaces with nanometer spatial and subpicosecond temporal resolutions. In this method, the secondary electron (SE) signal emitted from the sample’s surface is extremely sensitive to the surface dynamics and is detected in real time. In several unique applications, we spatially and temporally visualize the SE energy gain and loss, the charge carrier dynamics on the surface of InGaN nanowires and CdSe single crystal and its powder film. We also discuss the mechanisms for the observed dynamics, which will be the foundation for future potential applications of S-UEM to a wide range of studies on material surfaces and device interfaces.

Recent publication with Model IMPULSE from Clark-MXR

Time-resolved photoemission study of the electronic structure and dynamics of chemisorbed alkali atoms on Ru(0001)

Shengmin Zhang, Cong Wang, Xuefeng Cui, Yanan Wang, Adam Argondizzo, Jin Zhao, and Hrvoje Petek
Department of Physics and Astronomy and Pittsburgh Quantum Institute, University of Pittsburgh, & Department of Physics and ICQD/Hefei National Laboratory for Physical Sciences at Microscale, University of Science and Technology of China, Hefei,  China.

DOI: 10.1103/PhysRevB.93.045401

Abstract

We investigate the electronic structure and photoexcitation dynamics of alkali atoms (Rb and Cs) chemisorbed on transition-metal Ru(0001) single-crystal surface by angle- and time-resolved multiphoton photoemission. Three- and four-photon photoemission (3PP and 4PP) spectroscopic features due to the σ and π resonances arising from the ns and np states of free alkali atoms are observed from ∼2 eV below the vacuum level in the zero-coverage limit. As the alkali coverage is increased to a maximum of 0.02 monolayers, the resonances are stabilized by formation of a surface dipole layer, but in contrast to alkali chemisorption on noble metals, both resonances form dispersive bands with nearly free-electron mass. Density functional theory calculations attribute the band formation to substrate-mediated interaction involving hybridization with the unoccupied d bands of the substrate. Time-resolved measurements quantify the phase and population relaxation times in the three-photon photoemission (3PP) process via the σ and π resonances. Differences between alkali-atom chemisorption on noble and transition metals are discussed.

DNA extraction from geological samples assisted with Clark-MXR femtosecond laser micromachining technology

Traditional techniques used to extract DNA from thin sections of rock samples for amplification and analysis will often introduce contamination from the surrounding material. This is especially true when extracting microscopic inclusion in the presence of nearby unwanted materials. Our femtosecond laser micromachining capability offers a way to address these critical concerns.

This image shows a cylinder machined in a thin layer of a rock. The inclusion is isolated with negligible damage to either the center section or the surrounding area. And so that the trapped bio-matter in the middle of the circle can be analyzed without contamination of adjacent material.*

The Micromachining Job Shop at Clark-MXR has the capability, experience and know-how to help you in daunting tasks such as this one. See www.cmxr.com for more information or contact us at info@cmxr.com.

Clark-MXR will be at Photonics West. 



SPIE Photonics West
16-18 February 2016
San Francisco, California, USA
 
Please see us at Booth No. 3090 to discuss your ultrafast laser and micromachining needs

Imaging of Carrier Dynamics by Second-Generation 4D Scanning UEM enabled by Model IMPULSE from Clark-MXR. A new publication from Prof. Omar Abdelsaboor group at KAUST

Real-Space Imaging of Carrier Dynamics of Materials Surfaces by Second-Generation Four-Dimensional Scanning Ultrafast Electron Microscopy

Jingya Sun, Vasily A. Melnikov, Jafar I. Khan, and Omar F. Mohammed

Solar and Photovoltaics Engineering Research Center, Division of Physical Sciences and Engineering, King Abdullah University of Science and Technology (KAUST), Thuwal 23955-6900, Kingdom of Saudi Arabia

 Link to the Original Paper

Abstract

In the fields of photocatalysis and photovoltaics, ultrafast dynamical processes, including carrier trapping and recombination on material surfaces, are among the key factors that determine the overall energy conversion efficiency. A precise knowledge of these dynamical events on the nanometer (nm) and femtosecond (fs) scales was not accessible until recently. The only way to access such fundamental processes fully is to map the surface dynamics selectively in real space and time. In this study, we establish a second generation of four-dimensional scanning ultrafast electron microscopy (4D S-UEM) and demonstrate the ability to record time-resolved images (snapshots) of material surfaces with 650 fs and ∼5 nm temporal and spatial resolutions, respectively. In this method, the surface of a specimen is excited by a clocking optical pulse and imaged using a pulsed primary electron beam as a probe pulse, generating secondary electrons (SEs), which are emitted from the surface of the specimen in a manner that is sensitive to the local electron/hole density. This method provides direct and controllable information regarding surface dynamics. We clearly demonstrate how the surface morphology, grains, defects, and nanostructured features can significantly impact the overall dynamical processes on the surface of photoactive-materials. In addition, the ability to access two regimes of dynamical probing in a single experiment and the energy loss of SEs in semiconductor-nanoscale materials will also be discussed.

Another publication from Prof. Tony Heinz group with Clark-MXR's Model IMPULSE

Population inversion and giant bandgap renormalization in atomically thin WS₂ layers

Alexey Chernikov, Claudia Ruppert, Heather M. Hill, Albert F. Rigosi & Tony F. Heinz

Nature Photonics 9, 466–470 (2015) doi:10.1038/nphoton.2015.104

Abstract

Control of the optical properties of matter on ultrashort timescales is of both fundamental interest and central importance for applications in photonics. It is desirable to achieve pronounced changes over a broad spectral range using the least possible amount of material. Here, we demonstrate a dramatic change over a spectral range of hundreds of meV on the femtosecond timescale in the optical response of atomically thin two-dimensional crystals of the transition-metal dichalcogenide WS2 following excitation by intense optical pump pulses. Our findings reveal the role of extremely strong Coulomb interactions. At the direct gap, we observe a Mott transition from excitonic states to free carriers, accompanied by a giant bandgap renormalization of approximately 500 meV and the development of population inversion.