Molecular Collisions Now Imaged Better Than Ever

Molecular physicists from Radboud University Nijmegen have produced images of the changes in direction of colliding nitrogen monoxide molecules (NO) with unprecedented sharpness. 

By combining a Stark decelerator with advanced imaging techniques, they were able to obtain very high resolution images of the collision processes. 

The results were published in Nature Chemistry on 9 February. 

Read more here...

Visualisation of the collisions between NO and helium (left) and NO and neon (right). The top images show the research results of Van de Meerakker and his colleagues; the bottom images show the visualised theoretical predictions of the collisions. Red indicates a high probability of change of direction; blue indicates a low probability. The small peaks show the diffraction oscillations (Credits: Image Courtesy of Nature Chemistry).

Atomic Chemistry

Atom, smallest unit of a chemical element that can exist. In ancient Greek philosophy the word “atom” was used to describe the smallest bit of matter that could be conceived of. This “fundamental particle”, to use the present-day term for this concept, was thought of as indestructible; in fact, the Greek word for atom (atomos) means “not divisible”. 

Knowledge about the size and nature of the atom did not begin to be acquired until long after the beginnings of experimental science in the 16th and 17th centuries. Although many of the new “experimental philosophers” believed in the reality of atoms, the progress of science owed little to the idea. The first quantitative explanation of the behaviour of matter in terms of atoms was attempted by Daniel Bernoulli in 1738, but his work was largely ignored. However, chemistry was discovering things about matter that only the idea of atoms could explain. 

Chemists recognized that all liquids, gases, and solids can be broken down into their ultimate components, or elements. For example, salt is a chemical compound formed when the elements sodium and chlorine react together and become joined in an intimate form known as a chemical compound. Air, by contrast, was found to consist of a mixture of the gases nitrogen and oxygen, which do not react with each other.

Credit: library.thinkquest.org/

Particle in a 1-D Box

For detailed derivation click here.

Image credit: http://chemwiki.ucdavis.edu

Credit: http://www.cobalt.chem.ucalgary.ca/ziegler/Lec.chm373/Lec9/CHAPTER7.pdf

The Photoelectric Effect

The most dramatic prediction of Maxwell's theory of electromagnetism, published in 1865, was the existence of electromagnetic waves moving at the speed of light, and the conclusion that light itself was just such a wave.  Click me to find out more.

Courtesy: Michael Fowler, University of Virginia

Black Body Radiation

Do not all fix’d Bodies, when heated beyond a certain degree, emit Light and shine; and is not this Emission perform’d by the vibrating motion of its parts? For more click here.

Courtesy: Dr. Michael Fowler, University of Virginia

Sir James Chadwick - Birthday

James Chadwick was born on October 20, 1891, in Cheshire, England. He graduated from Manchester University's Honours School of Physics in 1911 and spent the next two years working on various radioactivity problems in the Physical Laboratory in Manchester, earning a M.Sc. degree in 1913 as well as the 1851 Exhibition Scholarship, which allowed him to continue his research and move to Berlin to work with Professor Hans Geiger. More here.

Sir James Chadwick

Courtesy: http://www.atomicarchive.com

Niels Bohr - 127 th Birthday

Niels Henrik David Bohr was born in Copenhagen on October 7, 1885, as the son of Christian Bohr, Professor of Physiology at Copenhagen University, and his wife Ellen, née Adler. Niels, together with his younger brother Harald (the future Professor in Mathematics), grew up in an atmosphere most favourable to the development of his genius - his father was an eminent physiologist and was largely responsible for awakening his interest in physics while still at school, his mother came from a family distinguished in the field of education.  For more click here.

 

Courtesy: http://www.nobelprize.org

Generate Quantum Numbers

Do you want to generate quantum numbers for an electronic configuration? Click on Quantum Number Primer below. It's an excellent illustration.

Quantum Number Primer

Courtesy: http://www.shsu.edu

Stern-Gerlach Experiment

Click to Run

Courtesy: PhET Interactive Simulations, University of Colorado,
                http://phet.colorado.edu/