Symmetry breaking by quantum coherence in single electron attachment

Quantum coherence-induced effects in atomic and molecular systems are the basis of several proposals for laser-based control of chemical reactions. So far, these rely on coherent photon beams inducing coherent reaction pathways that may interfere with one another, in order to achieve the desired outcome. This concept has been successfully exploited for removing the inversion symmetry in the dissociation of homonuclear diatomic molecules, but it remains to be seen if such quantum coherent effects can also be generated by interaction of incoherent electrons with such molecules. Here we show that resonant electron attachment to H2 and the subsequent dissociation into H (n=2) + H− is asymmetric about the inter-nuclear axis, while the asymmetry in D2 is far less pronounced. We explain this observation as due to attachment of a single electron resulting in a coherent superposition of two resonances of opposite parity. In addition to exemplifying a new quantum coherent process, our observation of coherent quantum dynamics involves the active participation of all three electrons and two nuclei, which could provide new tools for studying electron correlations as a means to control chemical processes and demonstrates the role of coherent effects in electron induced chemistry

Dissociation dynamics of transient anion formed via electron attachment to sulfur dioxide

We report the molecular dynamics of dissociative electron attachment to sulfur dioxide (SO2) by measuring the momentum distribution of fragment anions using the velocity slice imaging technique in the electron energy range of 2–10 eV. The S- channel results from symmetric dissociation which exhibits competition between the stretch mode and bending mode of vibration in the excited parent anion. The asymmetric dissociation of parent anions leads to the production of O- and SO- channels where the corresponding neutral fragments are formed in their ground as well as excited electronic states. We also identify that internal excitation of SO- is responsible for its low yield at higher electron energies

Dissociative Electron Attachment Cross Sections for H₂ and D₂

New measurements of the absolute cross sections for dissociative electron attachment (DEA) in molecular hydrogen and deuterium are presented which resolve previous ambiguities and provide a test bed for theory. The experimental methodology is based upon a momentum imaging time-of-flight spectrometer that allowed us to eliminate any contributions due to electronically excited metastable neutrals and ultraviolet light while ensuring detection of all the ions. The isotope effect in the DEA process in the two molecules is found to be considerably larger than previously observed. More importantly, it is found to manifest in the polar dissociation process (also known as ion pair production) as well

X-ray photoemission study of NiS_{2-x}Se_x (x = 0.0 - 1.2)

Electronic structure of NiS_{2-x}Se_x system has been investigated for various compositions (x) using x-ray photoemission spectroscopy. An analysis of the core level as well as the valence band spectra of NiS_2 in conjunction with many-body cluster calculations provides a quantitative description of the electronic structure of this compound. With increasing Se content, the on-site Coulomb correlation strength (U) does not change, while the band width W of the system increases, driving the system from a covalent insulating state to a pd-metallic state.Comment: 19 pages, 6 figures, To appear in Phys. Rev. B, 200

New Approaches to Spray Disinfectants to Fight Coronavirus

Our world is facing an unprecedented public health and economic crisis due to COVID-19. In this toughest challenging time, we are proposing some effective & affordable techniques for spraying disinfectants on each house, streets and roads of nation to help humanity to cope up with this calamity. We propose new spraying techniques and different type of disinfectants to disinfect larger areas repeatedly using two wheelers and other automobiles where larger vehicles can’t access and disinfect routinely. This will be effective in current as well as post lockdown pandemic era because very large population is involved in this movement andcommon public areas will be disinfected repeatedly and regularly without energy consumption

To what extent does disability discourage from work? An empirical analysis of labour force participation of disabled people in Italy

This paper is an empirical study on the work opportunities of people with disability using Italian data collected through a survey carried out by ISTAT in 2004. Our analysis is guided by the conceptual framework of the capability approach and investigates the role of conversion factors in the ability to be employed and the type of employment. We rst use a simple probit for labour force participation and then a sequential logit for the outcomes of participation as well as employment status. In all variants we nd that chronic illness is a stronger deterrent for labour force participation than disability. Women are more discouraged by disability compared to men. Among the various types of disabilities, `intellectual' disability is the strongest barrier as can be expected and hearing the least in uential. In a sequential decision-making process, we nd that disability a ects both labour force participation decision and the ability to be employed but not so much the choice between part-time and full-time

Electron attachment and quantum coherence in molecular hydrogen

Single electron attachment to a molecule may invoke quantum coherence in different angular momentum transfer channels. This has been observed in the 14 eV dissociative electron attachment resonance in molecular hydrogen where a coherent superposition of two negative ion resonant states of opposite parity is created, with the s and p partial waves of the electron contributing to the attachment process. Interference between the two partial wave contributions leads to a forward – backward asymmetry in the angular distribution of the product negative ions. Since these two resonant states dissociate to the same n = 2 state of H and H−, this asymmetry is further modified due to interference between the two paths of the dissociating molecular negative ion along different potential energy curves. This interference manifests as a function of the electron energy as well as isotopic composition. This case is akin to the quantum interference observed in photodissociation by one-photon vs two-photon absorption

Structural evolution drives diversification of the large LRR-RLK gene family

Cells are continuously exposed to chemical signals that they must discriminate between and respond to appropriately. In embryophytes, the leucine‐rich repeat receptor‐like kinases (LRR‐RLKs) are signal receptors critical in development and defense. LRR‐RLKs have diversified to hundreds of genes in many plant genomes. Although intensively studied, a well‐resolved LRR‐RLK gene tree has remained elusive. To resolve the LRR‐RLK gene tree, we developed an improved gene discovery method based on iterative hidden Markov model searching and phylogenetic inference. We used this method to infer complete gene trees for each of the LRR‐RLK subclades and reconstructed the deepest nodes of the full gene family. We discovered that the LRR‐RLK gene family is even larger than previously thought, and that protein domain gains and losses are prevalent. These structural modifications, some of which likely predate embryophyte diversification, led to misclassification of some LRR‐RLK variants as members of other gene families. Our work corrects this misclassification. Our results reveal ongoing structural evolution generating novel LRR‐RLK genes. These new genes are raw material for the diversification of signaling in development and defense. Our methods also enable phylogenetic reconstruction in any large gene family