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Native American Heritage Month at UCI: Franklin Dollar

November 10, 2020|UCI School of Physical Sciences|

Native American Heritage Month at Physical Sciences: This month, you’ll be hearing about Native Americans at the School of Physical Sciences, and how they make the School what it is.

I’m Franklin Dollar, a member of the Dry Creek Band of Pomo Indians and an Associate Professor in the Department of Physics & Astronomy at UCI. I study ultrafast laser matter interactions, and how we can convert laser energy into beams of particles and X-rays for next-generation microscopes. I also try to understand how physics education can be improved, from mentorship, to curriculum, to environment.

PS: What advice do you have for Native American students who are considering a career in STEM?

The most important thing you learn with a degree like physics is how to solve problems in the real world. This is useful in nearly any career, and can provide the flexibility to try out different career paths. So though you may not know what you want to do today, as you work and learn you will be able to find your own path.

 

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New electron microscope at CU Boulder enables groundbreaking research across disciplines—and from a distance

October 26, 2020|CU Boulder Research & Innovation Office|

Capable of achieving spatial resolutions of 70 pm—smaller than the size of an atom—the Thermo Scientific Titan Themis S/TEM, located in the newly-launched CU Facility for Electron Microscopy of Materials (CU FEMM), is now the highest-resolution electron microscope in Colorado.

Taller than a person and equipped with multiple cameras and detectors, this state-of-the-art, aberration-corrected electron microscopy platform makes groundbreaking research possible in a wide range of fields, including catalysis, advanced imaging, quantum information, energy conversion, biomaterials, battery research, geology, materials development and even archaeology. A team from the National Center for Atmospheric Research (NCAR) is even exploring a potential COVID-19 study using the microscope to inspect the salt from dried saliva droplets.

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UCLA scientists create world’s smallest ‘refrigerator’

September 22, 2020|UCLA Newsroom|

How do you keep the world’s tiniest soda cold? UCLA scientists may have the answer.

A team led by UCLA physics professor Chris Regan has succeeded in creating thermoelectric coolers that are only 100 nanometers thick — roughly one ten-millionth of a meter — and have developed an innovative new technique for measuring their cooling performance.

“We have made the world’s smallest refrigerator,” said Regan, the lead author of a paper on the research published recently in the journal ACS Nano.

To be clear, these miniscule devices aren’t refrigerators in the everyday sense — there are no doors or crisper drawers. But at larger scales, the same technology is used to cool computers and other electronic devices, to regulate temperature in fiber-optic networks, and to reduce image “noise” in high-end telescopes and digital cameras.

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Diffractive Imaging in a Flash

September 11, 2020|Science Editor's Choice|

Ultrashort light pulses on the time scale of attoseconds provide a window into some of the fastest electronic effects occurring in solid-state systems. Obtaining structural information through coherent diffractive imaging is usually done with monochromatic x-ray sources. However, ultrashort pulses are inherently broadband, and getting transient structural information on such short time scales is challenging. Rana et al. describe a method that works with the broadband nature of ultrashort pulses. They split the pulses into 17 different wavelengths and then used an algorithm to computationally stitch together the diffraction patterns from each wavelength to reveal the structural image optimized across all wavelengths. Demonstrating the technique at optical wavelengths illustrates the feasibility of applying the method to ultrafast x-ray pulses.

Phys. Rev. Lett. 125, 086101 (2020).

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Ultrafast Imaging at All Frequencies

August 19, 2020|APS Physics|

A new algorithm could allow researchers to capture attosecond, multiwavelength images of an object. Illuminating a sample with attosecond x-ray pulses could let researchers image phenomena as fleeting as the rearrangement of electrons during chemical reactions. The uncertainty principle dictates that ultrashort pulses have a broad energy spectrum. However, because focusing different wavelengths typically requires multiple sets of optics, most attempts at attosecond imaging are spectroscopic, ignoring all but one radiation frequency. Now, Jianwei Miao at the University of California, Los Angeles, and colleagues have developed an innovative algorithm that can simultaneously reconstruct multiple images of an object at different wavelengths using attosecond pulses. The method offers a way to take spectroscopic images without the need for sophisticated instruments.

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What to Know if You’re Teaching Physics Labs Remotely

August 5, 2020|JILA|

The coronavirus pandemic upended schools in the spring of 2020, sending students and faculty home. This rapidly changed how instructors handled laboratory physics courses. With a NSF RAPID grant, JILA Fellow Heather Lewandowski asked instructors what worked—and what didn’t—as they moved their lab courses online.

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Ultraviolet Laser Probes Nano-Film Stiffness

July 28, 2020|Optics & Photonics News|

Extremely thin films of dielectrics and other materials play vital roles in many types of advanced microelectronics, but their tiny dimensions and atomic make-up can impair mechanical performance.

Now, researchers at the NSF STROBE Science and Technology Center in the U.S. have shown they can characterize the mechanical properties of silicon-carbide films as thin as 5 nm using tabletop sources of extreme ultraviolet laser light—showing them to be far softer than thicker films of the same material (Phys. Rev. Mater., doi: 10.1103/PhysRevMaterials.4.073603).

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Scientists Open New Window into the Nanoworld

July 15, 2020|CU Boulder Today|

CU Boulder researchers have used ultra-fast extreme ultraviolet lasers to measure the properties of materials more than 100 times thinner than a human red blood cell. The team, led by scientists at JILA, reported its new feat of wafer-thinness this week in the journal Physical Review Materials. The group’s target, a film just 5 nanometers thick, is the thinnest material that researchers have ever been able to fully probe, said study coauthor Joshua Knobloch. “This is a record-setting study to see how small we could go and how accurate we could be,” said Knobloch, a graduate student at JILA, a partnership between CU Boulder and the National Institute of Standards and Technology (NIST). He added that when things get small, the normal rules of engineering don’t always apply. The group discovered, for example, that some materials seem to get a lot softer the thinner they become.

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Reading the Secrets of the Nanoworld with Infrared Light

May 21, 2020|The JILA Times|

Many of the life’s elementary processes and material properties are determined by how molecules couple and interact. Until recently, it’s been impossible to see how these molecules interact with each other with a high enough resolution. The Raschke Group has used infrared lasers and a new microscope to get a high-resolution view of molecular coupling in porphyrin nanocrystals.

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Researchers Capture Crystal Nucleation with Atomic Resolution in 4D (3D Plus Time)

May 11, 2020|DOE Office of Science|

A team of scientists has developed four-dimensional (the three dimensions of space plus the fourth dimension of time) atomic electron tomography. Tomography is a technique for creating images of cross sections of an object using X-rays or ultrasound. The technique directly images the dynamics of structural changes at the atomic scale during nucleation. Nucleation is the creation of structure in a vapor, solution, or liquid. The scientists found that the nuclei came in a broad range of shapes and sizes and possess a diffuse interface surrounding a stable core. Their observations challenge the long-held classical nucleation theory that posits nucleation begins with the formation of perfectly spherical nuclei that grow after they reach a certain critical size.

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