PRESS-NEWS.org - Press Release Distribution
PRESS RELEASES DISTRIBUTION

First direct band gap measurements of wide-gap hydrogen using inelastic X-ray scattering

First direct band gap measurements of wide-gap hydrogen using inelastic X-ray scattering
2021-01-26
(Press-News.org) Utilizing a newly developed state-of-the-art synchrotron technique, a group of scientists led by Dr. Ho-kwang Mao, Director of HPSTAR, conducted the first-ever high-pressure study of the electronic band and gap information of solid hydrogen up to 90 GPa. Their innovative high pressure inelastic X-ray scattering result serves as a test for direct measurement of the process of hydrogen metallization and opens a possibility to resolve the electronic dispersions of dense hydrogen. This work is published in the recent issue of Physical Review Letters.

The pressure-induced evolution of hydrogen's electronic band from a wide gap insulator to a closed gap metal, or metallic hydrogen, has been a longstanding problem in modern physics. However, hydrogen's remarkably high energy has prevented the electronic band gap from being directly observed under pressure before. Existing probes, such as electrical conductivity, optical absorption, or reflection spectroscopy measurements, are limited and provide little information on a wide-gap insulator. "All previous studies of the band gap in insulating hydrogen under compression were based on an indirect scheme using optical measurements," explains Dr. Mao.

The team used high-brilliance, high-energy synchrotron radiation to develop an inelastic x-ray (IXS) probe, yielding electronic band information of hydrogen in situ under high pressure in a diamond anvil cell (DAC). "The development of our DAC-IXS technique for this project took an international team of many experts in synchrotron inelastic X-ray spectroscopy, instrumentation, and ultra-high-pressure techniques over five years to complete," said Dr. Bing Li, the first author.

"Actually, the real beginning of this project can be traced back more than 20 years, and these results are the culmination of all that preparation and experimentation. A true testament to the enormous efforts and talents of the team involved," said Dr. Mao. The novel IXS probe technique enabled an inaccessible and extensive UV energy range of 45 eV to be measured, showing how dense hydrogen's electronic joint density of states and band gap evolve with pressure. The electronic band gap decreased linearly from 10.9 eV to 6.57 eV, with an 8.6 times densification from zero pressure up to 90 GPa.

These developments in state-of-the-art synchrotron capabilities with submicron to nanometer-scaled X-ray probes will only extend future experimental possibilities. Advances of IXS to higher pressure could place the semiconducting region of phases II-V within reach and enable the study of hydrogen metallization through direct and quantitative electronic band gap measurements.

This work overcomes formidable technical challenges, achieving direct experimental measurements of hydrogen's electronic band and its gap for the first time.

INFORMATION:

More information: Probing the Electronic Band Gap of Solid Hydrogen by Inelastic X-Ray Scattering up to 90 GPa, Li et al., Phys. Rev. Lett. 126, 036402.


[Attachments] See images for this press release:
First direct band gap measurements of wide-gap hydrogen using inelastic X-ray scattering

ELSE PRESS RELEASES FROM THIS DATE:

Wirelessly rechargeable soft brain implant controls brain cells

Wirelessly rechargeable soft brain implant controls brain cells
2021-01-26
A group of KAIST researchers and collaborators have engineered a tiny brain implant that can be wirelessly recharged from outside the body to control brain circuits for long periods of time without battery replacement. The device is constructed of ultra-soft and bio-compliant polymers to help provide long-term compatibility with tissue. Geared with micrometer-sized LEDs (equivalent to the size of a grain of salt) mounted on ultrathin probes (the thickness of a human hair), it can wirelessly manipulate target neurons in the deep brain using light. This study, led by Professor Jae-Woong Jeong, is a step forward from the wireless head-mounted ...

Gut microbiota reveals whether drug therapies work in inflammatory bowel diseases

2021-01-26
The prevalence of inflammatory bowel diseases has significantly increased both in Finland and globally. These disorders cannot be entirely cured. Instead, they are treated with anti-inflammatory drugs and, at times, through surgery. If conventional drug therapies based on anti-inflammatory drugs are ineffective, the diseases can be treated using infliximab, a biological TNF-α blocker that is administered intravenously. Infliximab is an antibody that prevents TNF-α, a pro-inflammatory factor, from binding with inflammatory cells in the intestine. It is effective in reducing inflammation and improving the patient's condition, while also controlling the disease well. Although infliximab therapy is often effective, roughly 30-40% of patients either do not respond ...

Change of course on the journey to the island of stability

Change of course on the journey to the island of stability
2021-01-26
An international research team succeeded in gaining new insights into the artificially produced superheavy element flerovium, element 114, at the accelerator facilities of the GSI Helmholtzzentrum für Schwerionenforschung in Darmstadt, Germany. Under the leadership of Lund University in Sweden and with significant participation of Johannes Gutenberg University Mainz (JGU) as well as the Helmholtz Institute Mainz (HIM) in Germany and other partners, flerovium was produced and investigated to determine whether it has a closed proton shell. The results suggest that, contrary to expectations, flerovium is not a so-called "magic nucleus". The results were published in ...

To find the right network model, compare all possible histories

To find the right network model, compare all possible histories
2021-01-26
Two family members test positive for COVID-19 -- how do we know who infected whom? In a perfect world, network science could provide a probable answer to such questions. It could also tell archaeologists how a shard of Greek pottery came to be found in Egypt, or help evolutionary biologists understand how a long-extinct ancestor metabolized proteins. As the world is, scientists rarely have the historical data they need to see exactly how nodes in a network became connected. But a new paper published in Physical Review Letters offers hope for reconstructing the missing information, using a new method to evaluate the rules that generate network models. "Network models are like impressionistic ...

Energy spent avoiding humans associated with smaller home ranges for male pumas

2021-01-26
A new paper from UC Santa Cruz researchers, published in END ...

How does incident solar radiation affect urban canyons?

How does incident solar radiation affect urban canyons?
2021-01-26
Overview: Jihui Yuan (Assistant Professor, Department of Architecture and Civil Engineering, Toyohashi University of Technology) proposed a numerical bead model to predict the upward-to-downward reflection ratio of glass bead retro-reflective (RR) material purposed for urban heat island (UHI) mitigation and reducing energy consumption. It revealed that the retro-reflectivity of glass bead RR material gradually increases from morning to noon, at which time it begins to gradually decrease. These results will contribute to existing research on the absorption or reflection of solar radiation to improve urban thermal and lighting ...

Addressing health disparities in diabetes requires a broader look at systemic racism

2021-01-26
WASHINGTON--Poor social conditions caused by systemic racism contribute to health disparities in people with diabetes, according to a paper published in the Endocrine Society's Journal of Clinical Endocrinology & Metabolism. Minorities are disproportionately affected by diabetes because of poor social conditions that contribute to negative health outcomes such as poverty, unsafe housing, lack of access to healthy food and safe physical activity, and inadequate employment and educational opportunities. These are known as the social determinants of health and are the result of residential ...

90-day vaginal ring shows promise as method for preventing both HIV and pregnancy

2021-01-26
PITTSBURGH, 26 January 2021 - A vaginal ring containing the antiretroviral drug dapivirine and the contraceptive hormone levonorgestrel delivered sustained levels of each drug when used continuously for 90 days - levels likely sufficient to serve its dual purpose for protecting against both HIV and unwanted pregnancy, according to findings of a new study. Results of the Phase I study of the 90-day dual-purpose ring are being presented at the HIV Research for Prevention (HIVR4P) Virtual Conference, or HIVR4P // Virtual, which is taking place over the course of ...

Crunch! Underwater acoustics expose 'shell-crushing' sounds in a large marine predator

2021-01-26
"Shell-crushing" - exactly what it sounds like - is a predatory mode used by numerous marine life from crabs to octopuses to large fishes and mammals when they eat hard-shelled mollusks like clams, oysters and conchs. These predators have to break apart the shell using robust claws or fortified jaws to access the prey's soft tissues. Despite its prevalence in the marine environment, this feeding behavior has remained elusive to study remotely, particularly for larger marine animals that destroy shells almost completely, leaving behind little trace. Moreover, because they are highly mobile, scientists have difficulty in directly observing their foraging habits, which is why the ecology of shell-crushing (durophagy) remains ...

Tungsten-substituted vanadium oxide breathes fresh air into catalyst technology

Tungsten-substituted vanadium oxide breathes fresh air into catalyst technology
2021-01-26
Tokyo, Japan - Researchers from Tokyo Metropolitan University have created a new tungsten-substituted vanadium oxide catalyst for breaking down harmful nitrogen oxides in industrial exhaust. Their new catalyst material works at lower temperatures and does not suffer major drops in performance when processing "wet" exhaust, resolving a major drawback in conventional vanadium oxide catalysts. They found that the unaggregated dispersal of atomic tungsten in the original crystal structure plays a key role in how it functions. Selective catalytic reduction (SCR) is an essential technology for keeping air clean. Industrial exhaust is passed through catalytic units and reacted with ...

LAST 30 PRESS RELEASES:

IOP Publishing and IPEM mandate reporting of sex and gender in research 

Dogs trained to detect trauma stress by smelling humans’ breath

Electronic device thermal management made simpler and slightly better!

Study: Dangerous surgical site infections can be reduced with simple prevention protocol

Genetic testing of patients with atrial fibrillation can alert clinicians to potential development of life-threatening conditions

Artificial Intelligence tool successfully predicts fatal heart rhythm

What progress has China made in agriculture green development over the past five years?

ALMA finds new molecular signposts in starburst galaxy

Open waste burning linked to air pollution in Northwestern Greenland

Google Street View reveals how built environment correlates with risk of cardiovascular disease

Connecting the dots to shape growth forces

Parental avoidance of toxic exposures could help prevent autism, ADHD in children, new study shows

Trends in the incidence of renal replacement therapy due to rapidly progressive glomerulonephritis in Japan, 2006–2021

Olympics not likely to swallow up skateboarding’s subversive nature into its corporate spectacle, study says

Looking after the NHS workforce must be a top priority, say experts

Prolonged use of certain hormone drugs linked to increased brain tumor risk

Delirium a ‘strong risk factor’ for dementia among older people

People experiencing homelessness more likely to develop dementia at younger ages, study finds

Can metalens be commercialized at a fraction of the cost?

Reclaim ‘wellness’ from the rich and famous, and restore its political radicalism, new book argues

Curtin research unlocks supernova stardust secrets

New documents reveal patient safety concerns over strike day cover

UTA hosts Solar-bration watch party for April 8 eclipse

Researchers discover molecule that promotes production of cancer cells in triple-negative breast cancer

New tool provides researchers with improved understanding of stem cell aging in the brain

Around half of people living with HIV in developed countries are now aged 50 years and over and at higher risk of becoming frail and having multiple comorbidities

You are never too old for an STI – more older adults being diagnosed with STIs such as gonorrhea and syphilis

University of Minnesota researchers introduce enhanced brain signal analysis technique

Aston University research center to focus on using AI to improve lives

Robot, can you say ‘cheese’?

[Press-News.org] First direct band gap measurements of wide-gap hydrogen using inelastic X-ray scattering