Search results: david casanova

Ever since the birth of quantum mechanics in the early twentieth century, chemists have struggled with a fundamental paradox. On one hand, Lewis dot structures and molecular drawings teach us to think of electrons as localized entities—either sitting neatly in lone pairs or shared directly between two bonding atoms. On the other hand, Schrödinger’s wave […]

Quantum computers promise to change how we calculate the behavior of electrons in molecules, but for the machines we have now — noisy, limited in size and coherence — the challenge is to squeeze the most chemistry out of the least quantum hardware. Now, a new paper introduces a practical trick to do exactly that: […]

Whenever an electric current flows a magnetic field is produced; as the orbital motion and the spin of atomic electrons are equivalent to tiny current loops, individual atoms create magnetic fields around them, when their orbital electrons have a net magnetic moment as a result of their angular momentum. The magnetic moment of an atom […]

Light emission (fluorescence or phosphorescence) in organic molecules, in the vast majority of cases, proceeds from the lowest energy excited state irrespective of the excitation energy used. This is known as the Kasha’s rule, which states that most of the molecules are emissive from the lowest energy, same (ground state) spin multiplicity, S1 excited state […]

An atomic state in which two spin angular momenta of electrons cancel each other, resulting in zero net spin, is called a singlet. If the angular momenta combine to give a total non-zero spin, then that state is called a triplet. A triplet state usually has lower, sometimes substantially lower, energy than a singlet. Importantly […]

Cromophores are generally groups of atoms having delocalized electrons. Covalent assemblies of conjugated organic chromophores provide the opportunity to engineer new excited states with novel properties. A team of researchers has now used a novel cage architecture for creating them. The properties of organic electronic materials being determined by the interactions between their conjugated subunits […]

Molecules when excited from their ground state (S 0 ) to their lowest electronically excited states often change their electronic structure considerably, which impacts on a range of important molecular properties. For example, the reactivity of a molecule in its excited state often differs markedly from that in its S 0 state. Also, the charge […]

A new fluorescent bicolour indicator, an organic molecule, could help detect the daughter atom of a neutrinoless double beta decay. If this is achieved, there would be an explanation to the matter-anti matter asymmetry in the universe. Experiments performed in 1909 by Geiger and Marsden, also called Rutherford gold foil experiment because Rutherford was their […]

We usually take for granted that aromaticity is something that belongs to the ground state of a molecule; but the fact is that nothing forbids aromaticity appearing in an excited state. In the same way that molecular properties are largely affected by the ground-state aromaticity, excited-state aromaticity can guide the understanding of excited-state processes, the […]

Many aromatic compounds can be made into organic semiconductors by doping them with a substance such as iodine, thereby producing mobile carriers of electric charge. This is analogous to the doping of silicon in an ordinary semiconductor. The benefits of using organic compounds are evident, namely, the resources are available everywhere, extremely cheap, and there […]