Nav: Home

Diamonds may be the key to future NMR/MRI technologies

December 16, 2015

Researchers with the U.S. Department of Energy (DOE)'s Lawrence Berkeley National Laboratory (Berkeley Lab) and the University of California (UC) Berkeley have demonstrated that diamonds may hold the key to the future for nuclear magnetic resonance (NMR) and magnetic resonance imaging (MRI) technologies

In a study led by Alexander Pines, a senior faculty scientist with Berkeley Lab's Materials Sciences Division and UC Berkeley's Glenn T. Seaborg Professor of Chemistry, researchers recorded the first bulk room-temperature NMR hyperpolarization of carbon-13 nuclei in diamond in situ at arbitrary magnetic fields and crystal orientations. The signal of the hyperpolarized carbon-13 spins showed an enhancement of NMR/MRI signal sensitivity by many orders of magnitude above what is ordinarily possible with conventional NMR/MRI magnets at room temperature. Furthermore, this hyperpolarization was achieved with microwaves, rather than relying on precise magnetic fields for hyperpolarization transfer.

Pines is the corresponding author of a paper in Nature Communications describing this study. The paper is titled "Room-temperature in situ nuclear spin hyperpolarization from optically pumped nitrogen vacancy centers in diamond."

Jonathan King, a member of Pines' research group is the lead author. Other co-authors are Keunhong Jeong, Christophoros Vassiliou, Chang Shin, Ralph Page, Claudia Avalos and Hai-Jing Wang.

The authors report the observation of a bulk nuclear spin polarization of six-percent, which is an NMR signal enhancement of approximately 170,000 times over thermal equilibrium. The signal of the hyperpolarized spins was detected in situ with a standard NMR probe without the need for sample shuttling or precise crystal orientation. The authors believe this new hyperpolarization technique should enable orders of magnitude sensitivity enhancement for NMR studies of solids and liquids under ambient conditions.

"Our results in this study represent an NMR signal enhancement equivalent to that achieved in the pioneering experiments of Lucio Frydman and coworkers at the Weizmann Institute of Science, but using microwave-induced dynamic nuclear hyperpolarization in diamonds without the need for precise control over magnetic field and crystal alignment," Pines says. "Room-temperature hyperpolarized diamonds open the possibility of NMR/MRI polarization transfer to arbitrary samples from an inert, non-toxic and easily separated source, a long sought-after goal of contemporary NMR/MRI technologies."

The combination of chemical specificity and non-destructive nature has made NMR and MRI indispensable technologies for a broad range of fields, including chemistry, materials, biology and medicine. However, sensitivity issues have remained a persistent challenge. NMR/MRI signals are based on an intrinsic quantum property of electrons and atomic nuclei called "spin." Electrons and nuclei can act like tiny bar magnets with a spin that is assigned a directional state of either "up" or "down." NMR/MRI signals depend upon a majority of nuclear spins being polarized to point in one direction - the greater the polarization, the stronger the signal. Over several decades Pines and members of his research group have developed numerous ways to hyperpolarize the spins of atomic nuclei. Their focus over the past two years has been on diamond crystals and an impurity called a nitrogen-vacancy (NV) center, in which optical and spin degrees of freedom are coupled.

"An NV center is created when two adjacent carbon atoms in the lattice of a pure diamond crystal are removed from the lattice leaving two gaps, one of which is filled with a nitrogen atom, and one of which remains vacant," Pines explains. "This leaves unbound electrons in the center between the nitrogen atom and a vacancy that give rise to unique and well-defined electron spin polarization states."

In earlier studies, Pines and his group demonstrated that a low-strength magnetic field could be used to transfer NV center electron spin polarization to nearby carbon-13 nuclei, resulting in hyperpolarized nuclei. This spin transference process - called dynamic nuclear polarization - had been used before to enhance NMR signals, but always in the presence of high-strength magnetic fields and cryogenic temperatures. Pines and his group eliminated these requirements by placing a permanent magnet near the diamond.

"In our new study we're using microwaves to match the energy between electrons and carbon-13 nuclei rather than a magnetic field, which removes some difficult restrictions on the strength and alignment of the magnetic field and makes our technique more easy to use," says King. "Also, in our previous studies, we inferred the presence of nuclear polarization indirectly through optical measurements because we weren't able to test if the bulk sample was polarized or just the nuclei that were very close to the NV centers. By eliminating the need for even a weak magnetic field, we're now able to make direct measurements of the bulk sample with NMR."

In their Nature Communications paper, Pines, King and the other co-authors say that hyperpolarized diamonds, which can be efficiently integrated into existing fabrication techniques to create high surface area diamond devices, should provide a general platform for polarization transfer.

"We envision highly enhanced NMR of liquids and solids using existing polarization transfer techniques, such as cross-polarization in solids and cross-relaxation in liquids, or direct dynamic nuclear polarization to outside nuclei from NV centers," King says, noting that such transfer of polarization to solid surface and liquids had been previously demonstrated by the Pines group using laser polarized Xe-129. "Our hyperpolarization technique based on optically polarized NV centers is far more robust and efficient and should be applicable to arbitrary target molecules, including biological systems that must be maintained at near ambient conditions."
-end-
This research was supported by the DOE Office of Science.

Lawrence Berkeley National Laboratory addresses the world's most urgent scientific challenges by advancing sustainable energy, protecting human health, creating new materials, and revealing the origin and fate of the universe. Founded in 1931, Berkeley Lab's scientific expertise has been recognized with 13 Nobel prizes. The University of California manages Berkeley Lab for the U.S. Department of Energy's Office of Science. For more, visit http://www.lbl.gov.

DOE's Office of Science is the single largest supporter of basic research in the physical sciences in the United States, and is working to address some of the most pressing challenges of our time. For more information, please visit the Office of Science website at science.energy.gov/.

DOE/Lawrence Berkeley National Laboratory

Related Magnetic Field Articles:

Scholes finds novel magnetic field effect in diamagnetic molecules
The Princeton University Department of Chemistry publishes research this week proving that an applied magnetic field will interact with the electronic structure of weakly magnetic, or diamagnetic, molecules to induce a magnetic-field effect that, to their knowledge, has never before been documented.
Origins of Earth's magnetic field remain a mystery
The existence of a magnetic field beyond 3.5 billion years ago is still up for debate.
New research provides evidence of strong early magnetic field around Earth
New research from the University of Rochester provides evidence that the magnetic field that first formed around Earth was even stronger than scientists previously believed.
Massive photons in an artificial magnetic field
An international research collaboration from Poland, the UK and Russia has created a two-dimensional system -- a thin optical cavity filled with liquid crystal -- in which they trapped photons.
Adhesive which debonds in magnetic field could reduce landfill waste
Researchers at the University of Sussex have developed a glue which can unstick when placed in a magnetic field, meaning products otherwise destined for landfill, could now be dismantled and recycled at the end of their life.
Earth's last magnetic field reversal took far longer than once thought
Every several hundred thousand years or so, Earth's magnetic field dramatically shifts and reverses its polarity.
A new rare metals alloy can change shape in the magnetic field
Scientists developed multifunctional metal alloys that emit and absorb heat at the same time and change their size and volume under the influence of a magnetic field.
Physicists studied the influence of magnetic field on thin film structures
A team of scientists from Immanuel Kant Baltic Federal University together with their colleagues from Russia, Japan, and Australia studied the influence of inhomogeneity of magnetic field applied during the fabrication process of thin-film structures made from nickel-iron and iridium-manganese alloys, on their properties.
'Magnetic topological insulator' makes its own magnetic field
A team of U.S. and Korean physicists has found the first evidence of a two-dimensional material that can become a magnetic topological insulator even when it is not placed in a magnetic field.
Scientists develop a new way to remotely measure Earth's magnetic field
By zapping a layer of meteor residue in the atmosphere with ground-based lasers, scientists in the US, Canada and Europe get a new view of Earth's magnetic field.
More Magnetic Field News and Magnetic Field Current Events

Trending Science News

Current Coronavirus (COVID-19) News

Top Science Podcasts

We have hand picked the top science podcasts of 2020.
Now Playing: TED Radio Hour

Listen Again: Meditations on Loneliness
Original broadcast date: April 24, 2020. We're a social species now living in isolation. But loneliness was a problem well before this era of social distancing. This hour, TED speakers explore how we can live and make peace with loneliness. Guests on the show include author and illustrator Jonny Sun, psychologist Susan Pinker, architect Grace Kim, and writer Suleika Jaouad.
Now Playing: Science for the People

#565 The Great Wide Indoors
We're all spending a bit more time indoors this summer than we probably figured. But did you ever stop to think about why the places we live and work as designed the way they are? And how they could be designed better? We're talking with Emily Anthes about her new book "The Great Indoors: The Surprising Science of how Buildings Shape our Behavior, Health and Happiness".
Now Playing: Radiolab

The Third. A TED Talk.
Jad gives a TED talk about his life as a journalist and how Radiolab has evolved over the years. Here's how TED described it:How do you end a story? Host of Radiolab Jad Abumrad tells how his search for an answer led him home to the mountains of Tennessee, where he met an unexpected teacher: Dolly Parton.Jad Nicholas Abumrad is a Lebanese-American radio host, composer and producer. He is the founder of the syndicated public radio program Radiolab, which is broadcast on over 600 radio stations nationwide and is downloaded more than 120 million times a year as a podcast. He also created More Perfect, a podcast that tells the stories behind the Supreme Court's most famous decisions. And most recently, Dolly Parton's America, a nine-episode podcast exploring the life and times of the iconic country music star. Abumrad has received three Peabody Awards and was named a MacArthur Fellow in 2011.