Doppler effect found even at molecular level -- 169 years after its discovery

ScienceDaily (May 11, 2011) — Whether they know it or not, anyone who's ever gotten a speeding ticket after zooming by a radar gun has experienced the Doppler effect -- a measurable shift in the frequency of radiation based on the motion of an object, which in this case is your car doing 45 miles an hour in a 30-mph zone.

But for the first time, scientists have experimentally shown a different version of the Doppler effect at a much, much smaller level -- the rotation of an individual molecule. Prior to this such an effect had been theorized, but it took a complex experiment with a synchrotron to prove it's for real.

"Some of us thought of this some time ago, but it's very difficult to show experimentally," said T. Darrah Thomas, a professor emeritus of chemistry at Oregon State University and part of an international research team that just announced its findings in Physical Review Letters, a professional journal.

Most illustrations of the Doppler effect are called "translational," meaning the change in frequency of light or sound when one object moves away from the other in a straight line, like a car passing a radar gun. The basic concept has been understood since an Austrian physicist named Christian Doppler first proposed it in 1842.

But a similar effect can be observed when something rotates as well, scientists say.

"There is plenty of evidence of the rotational Doppler effect in large bodies, such as a spinning planet or galaxy," Thomas said. "When a planet rotates, the light coming from it shifts to higher frequency on the side spinning toward you and a lower frequency on the side spinning away from you. But this same basic force is at work even on the molecular level."

In astrophysics, this rotational Doppler effect has been used to determine the rotational velocity of things such as planets. But in the new study, scientists from Japan, Sweden, France and the United States provided the first experimental proof that the same thing happens even with molecules.

At this tiny level, they found, the rotational Doppler effect can be even more important than the linear motion of the molecules, the study showed.

The findings are expected to have application in a better understanding of molecular spectroscopy, in which the radiation emitted from molecules is used to study their makeup and chemical properties. It is also relevant to the study of high energy electrons, Thomas said.

"There are some studies where a better understanding of this rotational Doppler effect will be important," Thomas said. "Mostly it's just interesting. We've known about the Doppler effect for a very long time but until now have never been able to see the rotational Doppler effect in molecules."

Story Source:

The above story is reprinted (with editorial adaptations by ScienceDaily staff) from materials provided by Oregon State University, via EurekAlert!, a service of AAAS.

Journal Reference:

T. D. Thomas, E. Kukk, K. Ueda, T. Ouchi, K. Sakai, T. X. Carroll, C. Nicolas, O. Travnikova, and C. Miron. Experimental observation of rotational Doppler broadening in a molecular system. Physical Review Letters, Accepted Apr 12, 2011

Note: If no author is given, the source is cited instead.

Disclaimer: Views expressed in this article do not necessarily reflect those of ScienceDaily or its staff.

View the original article here

Doppler effect found even at molecular level -- 169 years after its discovery

ScienceDaily (May 11, 2011) — Whether they know it or not, anyone who's ever gotten a speeding ticket after zooming by a radar gun has experienced the Doppler effect -- a measurable shift in the frequency of radiation based on the motion of an object, which in this case is your car doing 45 miles an hour in a 30-mph zone.

But for the first time, scientists have experimentally shown a different version of the Doppler effect at a much, much smaller level -- the rotation of an individual molecule. Prior to this such an effect had been theorized, but it took a complex experiment with a synchrotron to prove it's for real.

"Some of us thought of this some time ago, but it's very difficult to show experimentally," said T. Darrah Thomas, a professor emeritus of chemistry at Oregon State University and part of an international research team that just announced its findings in Physical Review Letters, a professional journal.

Most illustrations of the Doppler effect are called "translational," meaning the change in frequency of light or sound when one object moves away from the other in a straight line, like a car passing a radar gun. The basic concept has been understood since an Austrian physicist named Christian Doppler first proposed it in 1842.

But a similar effect can be observed when something rotates as well, scientists say.

"There is plenty of evidence of the rotational Doppler effect in large bodies, such as a spinning planet or galaxy," Thomas said. "When a planet rotates, the light coming from it shifts to higher frequency on the side spinning toward you and a lower frequency on the side spinning away from you. But this same basic force is at work even on the molecular level."

In astrophysics, this rotational Doppler effect has been used to determine the rotational velocity of things such as planets. But in the new study, scientists from Japan, Sweden, France and the United States provided the first experimental proof that the same thing happens even with molecules.

At this tiny level, they found, the rotational Doppler effect can be even more important than the linear motion of the molecules, the study showed.

The findings are expected to have application in a better understanding of molecular spectroscopy, in which the radiation emitted from molecules is used to study their makeup and chemical properties. It is also relevant to the study of high energy electrons, Thomas said.

"There are some studies where a better understanding of this rotational Doppler effect will be important," Thomas said. "Mostly it's just interesting. We've known about the Doppler effect for a very long time but until now have never been able to see the rotational Doppler effect in molecules."

Story Source:

The above story is reprinted (with editorial adaptations by ScienceDaily staff) from materials provided by Oregon State University, via EurekAlert!, a service of AAAS.

Journal Reference:

T. D. Thomas, E. Kukk, K. Ueda, T. Ouchi, K. Sakai, T. X. Carroll, C. Nicolas, O. Travnikova, and C. Miron. Experimental observation of rotational Doppler broadening in a molecular system. Physical Review Letters, Accepted Apr 12, 2011

Note: If no author is given, the source is cited instead.

Disclaimer: Views expressed in this article do not necessarily reflect those of ScienceDaily or its staff.

View the original article here

SpaceX Will Send Humans To Mars In the Next 10 to 20 Years

SpaceX's Dragon Spacecraft Separating from its Falcon 9 Carrier Rocket SpaceX, Courtesy of NASA

SpaceX will send humans to Mars within 10 to 20 years, according to an interview with its CEO in the Wall Street Journal. Elon Musk says his company will send people to space within three years, and he wants to colonize other planets next.

“I want SpaceX to help make life multi-planetary,” he said. “We’re going all the way to Mars, I think. Best case, 10 years, worst case, 15 to 20 years.”

In an interview with the Journal’s Alan Murray, Musk said he wants humans to build a self-sustaining base on Mars.

“A future when humanity is a spacefaring civilization, out there exploring the stars, is an incredibly exciting future,” he said.

The majority of the interview focuses on Tesla Motors’ efforts and the state of electric cars in the U.S., including price and availability and the problem of charging the vehicles. But Musk’s pronouncements about space colonization are far juicier, in our opinion.

He said SpaceX would be the transportation provider, not necessarily the colony-builder.

“We want to be like the shipping company that brought people from Europe to America, or like the Union Pacific railroad. Our goal is to facilitate the transfer of people and cargo to other planets, and then it’s going to be up to people if they want to go,” he said.

Along with developing several successful heavy-lift rockets for cargo, SpaceX aims to send astronauts to space for NASA and other clients. Last week, the company won a $75 million contract from NASA to make its Falcon 9 rocket and Dragon space capsule ready for humans. Sierra Nevada, Boeing and Blue Origin also won contracts to build capsules.

Last year, SpaceX became the first to launch a private spaceship into orbit and bring it home.

[Wall Street Journal]

View the original article here