2010 Newsletter

The J.R. Macdonald Laboratory has now firmly established AMO (Atomic, Molecular and Optical) ultrafast laser physics as its research theme. We hosted the 2nd International Conference on Attosecond Physics at the K-State Alumni center in July 2009. This successful meeting attracted more than 230 participants from all over the world. Chii-Dong Lin and Zenghu Chang were co-chairs and led our group effort to organize this meeting with the help of many others in our department and K-State.

The Kansas Light Source (KLS) continues to serve as our main workhorse, now scheduled essentially 24 hours per day 7 days per week. This laser delivers 25 fs, 800 nm pulses with 3 mJ of energy at 1.5 kilohertz. The pulse can be shortened to 6 fs and the phase of the “carrier” of the laser relative to the envelope can be stabilized. In spite of the efficient use of the KLS beam time, lack of laser time has been the main limiting factor on our experimental program. To alleviate this problem, we have submitted a few proposals for a new and more advanced laser system. Recently, one of these proposals was funded by DOE at approximately 1.3 million dollars. We plan to have this new laser system operational before the end of 2010.

In the meantime, Zenghu Chang’s group has been working hard to keep up with the high demand for laser time, while continuously developing new capabilities such as isolated 140 attosecond laser pulses. A “Dazzler”, a device capable of generating “designer” pulses by cutting out or modifying user-chosen slices of the wavelength range of the pulse, has been used by Brett DePaola’s group and by Eric Wells, from Augustana College, to control reaction dynamics of atoms and molecules. We were excited to see Lew Cocke’s collaborative research on the interaction of light with simple molecules in the prestigious Science magazine (Science v322, p1081). Lew’s group is conducting similar cutting-edge experiments in our laboratory, in which a short train of attosecond pulses is generated and used to probe atoms and molecules. Igor Litvinyuk’s group uses intense laser pulses for time-resolved imaging of molecules – Coulomb explosion imaging with COLTRIMS or velocity map imaging (VMI). Vinod Kumarappan has begun aligning and orienting complex molecules in space and imaging them using VMI tomography. The new permanent-magnet ECR ion source has been used by Steve Lundeen, from Colorado State Univ., to study uranium ions, and by Itzik Ben-Itzhak’s group to study fragmentation of molecular ions by intense ultrashort laser pulses.

The JRML theory effort has paralleled our experimental work. For example, Chii-Dong Lin’s group developed a quantitative rescattering (QRS) theory that can be used for dynamic chemical imaging of a transient molecule or to characterize the laser pulse, Uwe Thumm’s group developed tools to predict the effects of strong laser fields on the electronic and nuclear dynamics in molecules and adsorbate-covered metal surfaces, and Brett Esry’s group studied the behavior of simple benchmark atoms and molecules in ultrashort, intense laser pulses and developed a general theory of multi-color control.

The groups of Kristan Corwin and Brian Washburn specialize in nonlinear optics and photonic crystal fibers (PCF) and their use for frequency metrology and laser physics. They have a Department of Defense (DOD) and an NSF funded project to develop frequency references in PCFs. Using a phase stabilized fiber laser frequency comb, they measured to a 10 kHz accuracy an acetylene filled kagome PCF reference. They also have two DOD funded projects to develop a molecular gas laser inside a PCF.

Changes of key JRML personnel continued with the hiring of Dr. Matthias Kling, from MPQ Garching, Germany, as a new faculty member in our department. Professor Igor Litvinyuk resigned his faculty position this summer and moved to Griffith Univ., Australia. We are especially proud to report that Zenghu Chang and Brett Esry were recently appointed Ernest K. and Lillian E. Chapin Professors in recognition of their contributions to JRML and the Physics department. We have also had many changes in junior lab personnel. As new postdocs, Kun Zhao from the Univ. of Nebraska-Lincoln has joined Zenghu Chang’s group, and Guillaume Laurent from the Univ. of Madrid, Spain, has joined Lew Cocke’s group. A couple of our postdocs moved to new jobs: Kamal Singh – Assistant Professor at the Indian Institute of Science Education and Research (IISER), Mohali, Chandigarh, India, Karl Tillman – Research Faculty at the Institute for Shock Physics in Spokane, Hiroki Mashiko – post-doc at Lawrence Berkeley National Lab (LBNL), Ximao Feng – post-doc at K-State chemistry, Jarlath McKenna – post-doc at Imperial College, London, UK, and Feng He was offered a professorship in Shanghai University starting in the summer of 2010. Three of our graduate students (advisor) received their PhD’s and moved to postdoc or industry positions: Fatima Anis (Esry) still at K-State, Irina Bocharova (Litvinyuk) now at LBNL, Ioannis Chatzakis (Richard/Ben-Itzhak) now at Iowa State Univ. In addition, a few of our graduate students completed their MSc’s: Nora G. Johnson (Ben-Itzhak), Jianjun Hua (Esry), Maia Magrakvelidze (Litvinyuk/Thumm), Maia and Nora are presently working toward a PhD. New graduate students in the JRML include: Qi Zhang (Chang), Chenchen Wang (Corwin), Bachana Lomsadze (DePaola), Dustin Ursrey and Shuo Zeng (Esry), Varun Makhija (Kumarappan), and Aihua Liu (Thumm).

We have had a long parade of excellent colloquium speakers in AMO this year. Roland Wester from Univ. of Freiburg, Germany, Matthias Kling from the Max Planck Institute for Quantum Optics, Germany, Markus Guehr from Stanford Univ., and Karen Sauer from George Mason Univ.. Outside speakers at our AMO seminar this year have included Gerhard Paulus from the Univ. of Jena, Germany, and Texas A&M Univ., Christian Madsen from the Univ. of Aarhus, Denmark, Claus Peter Schulz from the Max-Born Institut, Germany, Andre Staudte from NRC Canada, Lars Madsen from the Univ. of Aarhus, Denmark, Kathy-Anne Soderberg from the Univ. of Chicago, Christine Aikins from KSU Chemistry, Michal Bajcsy from Harvard, and Valer Tosa from the Natl. Inst. R&D, Romania.

Kansas State University's world-renowned physics research with ultrafast intense lasers at the J. R. Macdonald Laboratory drew more than 200 top researchers from 25 countries to Manhattan for the Second International Conference on Attosecond Physics from July 28-Aug. 1.

The first Attosecond Physics Conference took place in 2007 in Dresden, Germany, at the Max Planck Institute for Complex Systems. Because of the J.R. Macdonald Laboratory's reputation, K-State was chosen to host the second conference.

Dean Zollman, university distinguished professor and head of K-State's department of physics, said that despite the global recession, more than 200 scientists were expected to attend the meeting, and more than half of them came from abroad, including almost all of the leading research groups from Europe, Asia and Canada. He said that this conference series was the new forum for the advancement of attosecond technology and science.

Chii-Dong Lin, K-State university distinguished professor of physics and conference co-chair, said that attosecond physics aims at measuring the motion of electrons in atoms, molecules and matter in their own time scale. An attosecond is one billion-billionth of a second.

"When a referee in a football game wants to make sure that a close play at the end zone is a fumble or a touchdown, he often has to rely on viewing the slow motion taken by a TV camera in order to follow how the actual event occurred," Lin said. "In all sports, by analyzing the films, an athlete can learn how to correct his or her technique. Similarly, to know how a chemical reaction ends up with a specific product, the scientists would like to be able to make a 'molecular movie' so they can follow its reaction path and then they can control it."

Because chemical reactions are the consequence of the rearrangement of electrons in the molecules, and the changes in motion of electrons occur on the very short time of attoseconds, attosecond scientists study how to make such ultrafast cameras and how to make measurement with these cameras. Because the molecular movie is not a simple picture, the scientists also must learn how to read the signals taken by them.

Attosecond light pulses were first generated in the 21st century. Today there are only a handful of laboratories in the world capable of making attosecond light pulses. At K-State, Zenghu Chang, professor of physics and a conference co-chair, is a member of this group. Under the guidance of 10 teaching faculty at the J.R. Macdonald Laboratory, more than 60 graduate students, postdoctoral research associates, research faculty and laboratory staff are engaged in research using ultrafast lasers, with funding support from U.S. Department of Energy, Army Research and the National Science Foundation.

As the attosecond technology becomes mature in the future, it would enable scientists to control chemical reactions at the most fundamental level and move the present-day nanotechnology to a new level. K-State's research is expected to contribute an integral part to this effort, Zollman said.

Pioneers of the field are who came to K-State and served as the conference honorary chairs included Ferenc Krausz of the Max Planck Institute for Quantum Optics in Germany, Paul Corkum of National Research Council of Canada and University of Ottawa, and Katsumi Midorikawa from RIKEN in Japan.

Several K-State scholars spoke at the conference. Ahn-Thu Le, research assistant professor at the J.R. Macdonald Laboratory, discussed using high harmonic generation to probe fixed-in-space molecular structures. Hiroki Mashiko, research associate in physics, discussed the fast laser technique of double optical gating. Pedrag Ranitovic, former K-State research associate in physics, discussed how using attosecond ultraviolet and femtosecond infrared radiation can probe the time dependence of the molecular dissociation process.

More information from the second International Conference in Attosecond Physics is available at http://jrm.phys.k-state.edu/Atto-09/.

Courtesy of K-State Media Relations
Sources: Zenghu Chang, 785-532-1621, chang@phys.ksu.edu;
Lew Cocke, 785-532-1609, cocke@phys.ksu.edu;
and Chii Dong Lin, 785-532-1617, cdlin@phys.ksu.edu.
Web site: http://jrm.phys.ksu.edu/Atto-09/
News release prepared by: Erinn Barcomb-Peterson, 785-532-6415, ebarcomb@k-state.edu
Monday, July 13, 2009

A Kansas State University physicist is continuing his study of atomic collisions with the help of a National Science Foundation grant awarded under the American Recovery and Reinvestment Act.

Brett Esry, professor of physics, received more than $282,000 from the National Science Foundation to study what happens when atoms collide in groups of three and four. These few-body collisions play an important role in experiments on ultracold quantum gasses. Esry said a better theoretical understanding of these collisions could help physicists improve design of experiments and interpretation of what has been measured. A better understanding of ultracold quantum gasses can potentially affect such technologically important phenomena as superconductivity and quantum computing.

Moreover, understanding few-body collisions can improve our understanding of chemistry in outer space, Esry said. One of the simplest reactions that forms molecules from atoms occurs when three atoms combine to form a diatomic molecule. That means these collisions play an important role in the chemistry of interstellar clouds and planetary atmospheres. At higher temperatures, these reactions become important to combustion.

Esry and his research group at K-State focus on these ultracold atomic systems and on understanding the dynamics of atoms and molecules in intense laser fields. Esry conducts his work in K-State's J.R. Macdonald Laboratory, which is funded by the U.S. Department of Energy.

Esry also is receiving a grant from the U.S. Air Force Office of Scientific Research for the project "Ultracold polar molecules: New phases of matter for quantum information and quantum control." This effort joins 10 research groups from these institutions: Georgetown University; the James Franck Institute at the University of Chicago; the Joint Quantum Institute at the University of Maryland; JILA at the University of Colorado and also affiliated with the National Institute of Standards and Technology; Durham University in the United Kingdom; and the University of Innsbruck in Austria.

K-State's Macdonald Laboratory also is the recipient of a grant from the U.S. Department of Energy made possible by the American Recovery and Reinvestment Act. The nearly $1.3 million grant builds the infrastructure of the lab, adding a new laser system with nearly 10 times the capability of the current system, said Itzik Ben-Itzhak, the lab's director.

"This new laser system represents a substantial investment by the Department of Energy in our lab and its continued productivity, as well as a clear recognition of Kansas State University's strong commitment to our program."

With these awards, Esry and the other nine faculty who work in the lab and the larger atomic, molecular and optical physics group bring nearly $5 million dollars per year to K-State, Ben-Itzhak said.

Courtesy of K-State Media Relations
Source: Brett Esry, 785-532-1630, esry@phys.ksu.edu
News release prepared by: Erinn Barcomb-Peterson, 785-532-6415, ebarcomb@k-state.edu
Wednesday, Sept. 30, 2009

Ultrafast laser research at Kansas State University has allowed physicists to build on Nobel Prize-winning work in photo-electronics by none other than Albert Einstein.

Einstein received the Nobel Prize in 1921 for his theoretical explanation in 1905 of the so-called photo-effect -- that is, the emission of electrons from a metal surface by incident light.

In Einstein's time, laboratory light sources provided light of very low intensity in comparison with modern lasers like those at K-State. Back then, experiments could measure the energy -- or speed -- of light-emitted electrons but could not resolve their motion in time. In modern laboratories, lasers are used as light sources that provide very short and intensive flashes of light.

Uwe Thumm, K-State professor of physics, and Chang-hua Zhang, a postdoctoral research associate in physics, are theorists who have developed a model that allows them to compute not just the energy of photo-emitted electrons, but also the times after their release at which they can be detected. Within their quantum mechanical model, Thumm and Zhang found that electrons that are emitted by ultra-short laser pulses from different parts of a metal surface will arrive at an electron detector at slightly different times.

"It's a feat that would be impossible without high-intensity lasers like those at K-State's J. R. Macdonald Laboratory," Thumm said. "With the help of ultrashort laser pulses, the motion of electrons can now be followed in time. This has started an entire new area of research, called attosecond physics."

An attosecond is a billionth of a billionth of a second. It's an incredibly short time to humans -- but not to electrons, Thumm said.

"Fifty attoseconds is about the time resolution needed to resolve the motion of electrons in matter," he said.

In agreement with a recent experiment, their calculation shows that electrons of a metal surface that are near atomic nuclei are photo-emitted with a delay of about 110 attoseconds relative to another type of electron. These conduction electrons are not attached to individual atoms and enable metals to conduct electricity.

Thumm and Zhang published their work in Physical Review Letters in March. Their research was supported by the National Science Foundation and the U.S. Department of Energy.

Thumm said that Einstein's research, which laid the groundwork for their own research, is often understood as a proof for light behaving as a particle called a photon rather than as a wave. Einstein showed that only light above a certain minimal frequency -- in the blue end of the visible spectrum -- could make metals emit electrons.

"It was a celebrated model, and it's still in textbooks as an explanation that light is made up of photons," Thumm said. "You can talk to a lot of physics students who get it wrong."

While Einstein's model is not wrong, it is not a proof for the particle-character of light, Thumm said. Einstein published his model about two decades before modern quantum theory was developed. Modern quantum theory of matter predicts the emission of an electron even when light is regarded as a classical electro-magnetic wave.

Today, physicists have lasers that provide light at such high intensities that electrons can be emitted at lower frequencies, toward the red end of the visible spectrum. And today, scientists look at light as behaving both like a particle and a wave.

"There is a bit of a philosophical debate," Thumm said.

Thumm said that the new and exciting part of this research is that short pulses from ultrafast lasers like the Kansas Light Source at K-State's J.R. Macdonald Lab allow physicists to measure the timing of electrons emitting from metals, thus building on models like the one he and Zhang developed.

Researchers can use short, intense pulses of extreme ultraviolet light to get a tungsten surface to emit electrons. They can synchronize these extreme ultraviolet pulses with a delayed infrared pulse, into which the electron is emitted. Thumm said that this infrared pulse changes the energy of the emitted electrons over time and serves as a measuring stick to judge the timing of the electron emissions.

He said that it is a bit like how high-speed photography in the 19th century proved that all four of a horse's hooves leave the ground while running.

"In this case it's not the horse's hooves but the electrons that we're seeing," Thumm said. "The bigger picture is that if we resolve in time how electrons move, we can understand the timing of chemical reactions taking place. We can understand the basics of chemistry, biology and life."

While Thumm and other K-State physicists continue to delve further into attosecond research, the university will be host to the Second International Conference on Attosecond Physics from July 28 to Aug. 1, bringing physicists from around the world to the K-State campus in Manhattan.

More information on recent attosecond research at K-State is available online at http://jrm.phys.ksu.edu.

Courtesy of K-State Media Relations
Source: Uwe Thumm, 785-532-1613, thumm@phys.ksu.edu
Pronouncer: Uwe is "OOH-ve" -- with "e" as in Emily, and Thumm sounds like "tomb."
News release prepared by: Erinn Barcomb-Peterson, 785-532-6415, ebarcomb@k-state.edu.

Nora Johnson of Dell Rapids, SD, is one of three Kansas State University students who won a 2009 Fulbright U.S. Student scholarships for travels abroad. Nora received a one-year fellowship. She is among more than 1,500 U.S. citizens who are traveling abroad for the 2009-2010 academic year through the Fulbright program.

K-State now has had 50 Fulbright student scholars since 1975.

"I admire all of these students for choosing to step outside their comfort zone in order to learn and live in an international setting next year," said Jim Hohenbary, K-State assistant dean for nationally competitive scholarships. "I know they will do a great job in making connections and building goodwill between their host countries and the United States, and it is exciting to think that K-State is going to be represented in Germany."

The Fulbright U.S. Student Program offers fellowships for study abroad, research abroad or English teaching assistantships. The program aims to increase mutual understanding between the people of the United States and the people of other countries. Recipients are selected on the basis of academic or professional achievement as well as leadership potential. The Fulbright program was established under legislation introduced by late Sen. J. William Fulbright of Arkansas and is administered by the Institute of International Education.

Johnson is a graduate student in atomic, molecular and optical physics. She is using the Fulbright Scholarship to study laser-molecule interaction in Germany. Johnson works with Itzik Ben-Ithzak, K-State professor of physics, in a research group studying molecular physics. She has co-authored numerous publications that have appeared in journals such as Physics Review A and the Review of Scientific Instruments.

Johnson would like a career in an academic setting with an even workload of research and teaching duties. She graduated from Augustana College, Sioux Falls, S.D., with a bachelor's in chemistry and mathematics in 2005. At K-State, she has received the Timothy R. Donoghue scholarship. Johnson is a member of the Manhattan Ultimate Summer League, the Graduate Physics Student Association and the American Physics Society. A 2001 graduate of Flandreau Public High School, Flandreau, S.D., she is the daughter of Lawrence and Diane Johnson, Dell Rapids, S.D.

Courtesy of K-State Media Relations