Featured Research

from universities, journals, and other organizations

Cornell Research Team Makes Fundamental Discovery About Nature Of Hydrogen Combustion

Date:
November 8, 2000
Source:
Cornell University
Summary:
A Cornell University research team has uncovered the mechanics of a critical reaction in the combustion of hydrogen that could have implications for the future of energy production. Because of growing concerns about future energy sources based on fossil fuels -- concerns that range from supply to global warming -- considerable experimental and theoretical research is underway to better understand energy conversion processes, particularly those involving hydrogen.

ITHACA, N.Y. -- A Cornell University research team has uncovered the mechanics of a critical reaction in the combustion of hydrogen that could have implications for the future of energy production.

Because of growing concerns about future energy sources based on fossil fuels -- concerns that range from supply to global warming -- considerable experimental and theoretical research is underway to better understand energy conversion processes, particularly those involving hydrogen. The element, which is readily formed through the electrolysis of water and leaves only water as its combustion byproduct, is viewed as an attractive future material for use in heating and the internal combustion engine.

"The process we are studying is one of the most fundamental steps in combustion," says principal investigator Floyd Davis, associate professor of chemistry and chemical biology at Cornell. "Of course, ultimately the goal is to develop more efficient ways to convert energy from one form to another, but what we are doing is more fundamental: to study how energy is released in this reaction."

The researchers' report appears in the latest issue (Nov. 3) of the journal Science . Other authors are Davis's graduate students, Brian R. Strazisar and Cheng Lin. Their experimental report and a separate theoretical research paper by another group are discussed in an accompanying article by George C. Schatz, a Northwestern University chemist. The importance of the two papers, Schatz says, is that they "present important new results concerning a topic of longstanding interest to chemists, namely the relationship between reagent and product vibrational motions and the dynamics of chemical reactions."

Davis explains that during the combustion of hydrogen in air, energy is released in the form of heat, which to the observer appears as a hot flame. But at a submicroscopic level, the energy is released when the newly formed water molecules are produced in excited vibrational and rotational levels. The question, Davis says, is "how is this energy distributed?" The question, he notes, is important in the development of theoretical models to understand how energy flows in chemical reactions.

To find the answer, Davis and his coworkers used a technique called crossed molecular beams in which two separate molecular beams cross at right angles. Four lasers were used to measure the angular and velocity distributions of newly formed chemical products.

"A chemical reaction results from successful collisions between molecules," says Davis. "If the orientation of the reactants [the colliding molecules] is correct, they can pass through a critical configuration known as the transition state, allowing products to be formed."

In the reaction studied by Davis and his colleagues, the oxygen atom in a hydroxyl radical (OH) grabs an atom from deuterium (D2), forming water called monodeuterated water (HOD) and a deuterium atom. A hydroxyl radical is an oxygen atom connected by a single bond to a hydrogen atom. Deuterium, or heavy hydrogen, is an isotope of hydrogen, or a hydrogen atom with a neutron added. In all, the reaction involved four atoms and six dimensions.

"By observing where the products are scattered, and by measuring their velocities, we can learn about the details of the reactive encounter," says Davis.

He likens the effect to a game of baseball. When a batter hits a line drive, it is because the bat has struck the ball head-on. A pop fly results when the bat hits the ball slightly below its center. By watching where the "baseball" goes, researchers can learn about its collision with the "bat." In nature, molecules bump into each other constantly, but in most cases collisions don't lead to a reaction. Thus researchers are interested in how the probability of a reaction depends on the details of the collision.

A closely related issue is how energy is distributed into newly formed molecules following chemical reactions. In the reaction involving the formation of HOD+D, the Cornell group found that the HOD is primarily formed with two quanta of vibrational energy in the oxygen-deuterium (OD) bond. A quantum is the smallest "package" of energy that can be observed.

"The significance of this measurement is that since the 1980s, theory predicted that the energy would be deposited nearly statistically into all of the vibrational modes of HOD," says Davis. Recently, though, new calculations predicted that energy would instead appear only in certain HOD vibrational modes. The Cornell experimental measurements are in nearly total agreement with these theoretical results. "This is a breakthrough in our understanding of the way a reaction occurs," says Davis. The Science article is titled "Mode-Specific Energy disposal in the Four-Atom Reaction

OH + D2 --> HOD + D."

Related Web site:

o Davis Group Molecular Reaction Dynamics:http://www.chem.cornell.edu/hfd1/index.html


Story Source:

The above story is based on materials provided by Cornell University. Note: Materials may be edited for content and length.


Cite This Page:

Cornell University. "Cornell Research Team Makes Fundamental Discovery About Nature Of Hydrogen Combustion." ScienceDaily. ScienceDaily, 8 November 2000. <www.sciencedaily.com/releases/2000/11/001106060131.htm>.
Cornell University. (2000, November 8). Cornell Research Team Makes Fundamental Discovery About Nature Of Hydrogen Combustion. ScienceDaily. Retrieved July 24, 2014 from www.sciencedaily.com/releases/2000/11/001106060131.htm
Cornell University. "Cornell Research Team Makes Fundamental Discovery About Nature Of Hydrogen Combustion." ScienceDaily. www.sciencedaily.com/releases/2000/11/001106060131.htm (accessed July 24, 2014).

Share This




More Matter & Energy News

Thursday, July 24, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Robot Parking Valet Creates Stress-Free Travel

Robot Parking Valet Creates Stress-Free Travel

AP (July 23, 2014) 'Ray' the robotic parking valet at Dusseldorf Airport in Germany lets travelers to avoid the hassle of finding a parking spot before heading to the check-in desk. (July 23) Video provided by AP
Powered by NewsLook.com
Boeing Ups Outlook on 52% Profit Jump

Boeing Ups Outlook on 52% Profit Jump

Reuters - Business Video Online (July 23, 2014) Commercial aircraft deliveries rose seven percent at Boeing, prompting the aerospace company to boost full-year profit guidance- though quarterly revenues missed analyst estimates. Bobbi Rebell reports. Video provided by Reuters
Powered by NewsLook.com
Europe's Car Market on the Rebound?

Europe's Car Market on the Rebound?

Reuters - Business Video Online (July 23, 2014) Daimler kicks off a round of second-quarter earnings results from Europe's top carmakers with a healthy set of numbers - prompting hopes that stronger sales in Europe will counter weakness in emerging markets. Hayley Platt reports. Video provided by Reuters
Powered by NewsLook.com
9/11 Commission Members Warn of Terror "fatigue" Among American Public

9/11 Commission Members Warn of Terror "fatigue" Among American Public

Reuters - US Online Video (July 22, 2014) Ten years after releasing its initial report, members of the 9/11 Commission warn of the "waning sense of urgency" in combating terrorists attacks. Mana Rabiee reports. Video provided by Reuters
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:

Breaking News:
from the past week

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile: iPhone Android Web
Follow: Facebook Twitter Google+
Subscribe: RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins