Publications by authors named "Atanu Bhattacharya"

This study introduces a conceptually novel polynomial encoding algorithm for simulating potential energy operators encoded in diagonal unitary forms in a quantum computing machine. The current trend in quantum computational chemistry is effective experimentation to achieve high-precision quantum computational advantage. However, high computational gate complexity and fidelity loss are some of the impediments to the realization of this advantage in a real quantum hardware.

View Article and Find Full Text PDF

Ultraviolet and vacuum ultraviolet photo-absorption spectra of azido (-N3)-based energetic plasticizer, bis(1,3-diazido-prop-2-yl)-malonate (abbreviated as BDAzPM), in the gas phase is recorded at room temperature and in the photon energy range of 5.5-9.9 eV using a synchrotron radiation source.

View Article and Find Full Text PDF
Article Synopsis
  • Long-term monitoring of High Mountain Asian glaciers is essential as they support river flow in Asia, and recent data shows increasing rates of glacier mass loss in most regions since the 1960s.
  • Glacier mass budgets show significant variability, with rates as low as -0.06 m w.e.a in Eastern Pamir and as high as -0.40 m w.e.a in Central and Northern Tien Shan.
  • The primary driver of this escalating mass loss is rising summer temperatures, which now impact regions that previously maintained a balance between temperature and precipitation.
View Article and Find Full Text PDF
Article Synopsis
  • - The text discusses a versatile spectrometer for time-resolved photoemission spectroscopy, specifically tailored for analyzing liquid microjets using extreme UV and X-ray radiation.
  • - It highlights features designed to enhance energy resolution and detection capabilities, including optional retarding potentials and a specially developed gated electron detector that minimizes interference from surrounding light.
  • - Performance validation was conducted at SPring-8 and SACLA, showcasing its effectiveness in studying ultrafast charge transfer reactions in solutions, using a combination of UV laser and hard X-ray probes.
View Article and Find Full Text PDF

One of the factors that limits the application of the single active electron (SAE) formalism to simulate the high harmonic generation (HHG) spectra of atoms and molecules using the time-dependent Schrödinger equation (TDSE) is the unknown model effective one-dimensional potential energy (()) curve for the SAE. In the present contribution, we show that () can be constructed from the one-dimensional molecular electrostatic potential (MEP) of the respective cation to access theoretical HHG spectra not only for simple atoms but also for multielectron complex molecules.

View Article and Find Full Text PDF

Heterogeneous glacier mass loss has occurred across High Mountain Asia on a multi-decadal timescale. Contrasting climatic settings influence glacier behaviour at the regional scale, but high intra-regional variability in mass loss rates points to factors capable of amplifying glacier recession in addition to climatic change along the Himalaya. Here we examine the influence of surface debris cover and glacial lakes on glacier mass loss across the Himalaya since the 1970s.

View Article and Find Full Text PDF

The influence of hydrogen bonding and the associated attosecond hole delocalization on the high-order harmonic generation (HHG) process is investigated with the help of hydrogen-bonded binary mixture of acetonitrile and chloroform solvent vapors. We observe a strong enhancement of the HH yield compared to the results obtained with pure samples. We propose that the observed increase of HHG efficiency is due to the presence of hydrogen-bonded binary mixture.

View Article and Find Full Text PDF

The combined results of ab initio electronic-structure calculations, nonadiabatic molecular dynamics simulations using ab initio multiple spawning, and previous spectroscopic investigations of jet-cooled molecules provide strong evidence of a (π,σ)-mediated decomposition mechanism for the furazan and triazole energetic molecules. The importance of dissociative excited states formed by electron promotion from a π molecular orbital to a σ molecular orbital is explored for the furazan and triazole energetic molecules. Dissociative (π,σ) states of furazan and triazole energetic molecules can be populated by nonadiabatic surface jump from the (π,π) or the (n,π) state.

View Article and Find Full Text PDF

Energetic materials store a large amount of chemical energy. Different ignition processes, including laser ignition and shock or compression wave, initiate the energy release process by first promoting energetic molecules to the electronically excited states. This is why a full understanding of initial steps of the chemical dynamics of energetic molecules from the excited electronic states is highly desirable.

View Article and Find Full Text PDF

Molecular attosecond science has already started contributing to our fundamental understanding of ultrafast purely electron dynamics in isolated molecules under vacuum. Extending attosecond science to the liquid phase is expected to offer new insight into the influence of a surrounding solvent environment on the attosecond electron dynamics in solvated molecules. A systematic theoretical investigation of the attochemistry of solvated molecules would help one design attosecond experiments under ambient conditions to explore the attochemistry in a liquid environment.

View Article and Find Full Text PDF

Conical intersections are now firmly established to be the key features in the excited electronic state processes of polyatomic energetic molecules. In the present work, we have explored conical intersection-mediated nonadiabatic chemical dynamics of a simple analogue nitramine molecule, dimethylnitramine (DMNA, containing one N-NO energetic group), and its complex with an iron atom (DMNA-Fe). For this task, we have used the ab initio multiple spawning (AIMS) dynamics simulation at the state averaged-complete active space self-consistent field(8,5)/6-31G(d) level of theory.

View Article and Find Full Text PDF

Introduction: Reference data for European Organization for Research and Treatment of Cancer (EORTC) quality of life questionnaires do not include studies from the Indian subcontinent. The objective of the current study was to establish a reference dataset for Indian patients of non-small cell lung cancer (NSCLC) presenting with brain metastases (BM).

Material And Methods: One hundred forty patients with NSCLC with BM treated between 2012-2015 were registered in a prospective cohort study (CTRI/2013/01/003299).

View Article and Find Full Text PDF

In general, charge migration can occur via pure electron-electron correlation and relaxation or via coupling with nuclear motion. We must understand both aspects of charge migration through the non-hydrogen noncovalent bonds to harness full potential of the halogen-, chalcogen-, pnicogen- and tetrel-bonded photosensitive functional materials. This feature article, however, is focused on the pure relaxation- and correlation-driven charge migration, subsequent charge localization, and finally on charge-directed reactivity in the non-hydrogen noncovalent bonded clusters.

View Article and Find Full Text PDF

In this article, we have presented ultrafast charge transfer dynamics through halogen bonds following vertical ionization of representative halogen bonded clusters. Subsequent hole directed reactivity of the radical cations of halogen bonded clusters is also discussed. Furthermore, we have examined effect of the halogen bond strength on the electron-electron correlation- and relaxation-driven charge migration in halogen bonded complexes.

View Article and Find Full Text PDF

Decomposition of electronically excited nitro-containing molecules with different X-NO(2) (X = C, N, O) moieties has been intensively investigated over the past decades; however, their decomposition behavior has not previously been compared and contrasted. Comparison of their unimolecular decomposition behavior is important for the understanding of the reactivity differences among electronically excited nitro-containing molecules with different X-NO(2) (X = C, N, O) bond connections. Nitromethane (NM), dimethylnitramine (DMNA), and isopropylnitrate (IPN) are used as model molecules for C-NO(2), N-NO(2), and O-NO(2) active moieties, respectively.

View Article and Find Full Text PDF

The radical cationic reactivity of the peptide analogue molecule CH(3)CO-Gly-NH(2) is addressed both experimentally and theoretically. The radical cation intermediate of CH(3)CO-Gly-NH(2) is created by single-photon ionization of this molecule at 118.22 nm (~10.

View Article and Find Full Text PDF

Electronically nonadiabatic processes such as ultrafast internal conversion (IC) from an upper electronic state (S(1)) to the ground electronic state (S(0)) though a conical intersection (CI), can play an essential role in the initial steps of the decomposition of energetic materials. Such nonradiative processes following electronic excitation can quench emission and store the excitation energy in the vibrational degrees of freedom of the ground electronic state. This excess vibrational energy in the ground electronic state can dissociate most of the chemical bonds of the molecule and can generate stable, small molecule products.

View Article and Find Full Text PDF

Decomposition of excited electronic state s-tetrazine and its energetic derivatives, such as 3-amino-6-chloro-1,2,4,5-tetrazine-2,4-dioxide (ACTO), and 3,3(')-azobis (6-amino-1,2,4,5-tetrazine)-mixed N-oxides (DAATO(3.5)), is investigated through laser excitation and resonance enhanced multi photon ionization techniques. The N(2) molecule is detected as an initial product of the s-tetrazine decomposition reaction, through its two photon, resonance absorption transitions [a(") (1)Σ(g)(+) (v(') = 0) ← X (1)Σ(g)(+) (v(") = 0)].

View Article and Find Full Text PDF

Energetic materials store a large amount of chemical energy that can be readily converted into mechanical energy via decomposition. A number of different ignition processes such as sparks, shocks, heat, or arcs can initiate the excited electronic state decomposition of energetic materials. Experiments have demonstrated the essential role of excited electronic state decomposition in the energy conversion process.

View Article and Find Full Text PDF

The reactivity of radical cation carboxylic acids is investigated on the basis of mass spectrometry, infrared-vacuum ultraviolet (IR-VUV) photoionization spectroscopy, and high level correlated ab initio calculations. Their reactivity is found to be highly conformation specific and is governed by their initial charge distribution following ionization. In the present work, the radical cations of lactic acid, pyruvic acid, glycine, and valine are studied to probe their stability and conformation specific reactivity following single photon, vertical ionization at 10.

View Article and Find Full Text PDF

Lipids extracted from foods fried in thermally polymerized palm oil were evaluated in papads, French fries and fish fry (Bombay duck) with moisture content ranging between 10% and 75%, in an attempt to investigate the effect of moisture content on lipid quality indices such as free fatty acids, conjugated dienes, p-anisidine value, viscosity, total polar materials and colour values. The quality of lipids in products with high moisture content (50% or more) was found to be inferior to that of the oil left after frying, as evidenced in Bombay duck and French fries from potatoes with initial moisture content of 52-77%. A reverse trend was observed in papads and French fries prepared from dehydrated potatoes with moisture content of 12% or less.

View Article and Find Full Text PDF

Single injection of streptozotocin (STZ) resulted diabetes mellitus which was reflected here by the levels of fasting blood glucose and serum insulin. Moreover, this experimental diabetes also resulted testicular dysfunctions evaluated by count, viability and motility of sperm as well as by the activities of key enzymes for androgen synthesis. Diabetes induced testicular oxidative stress has been indicated here by the monitoring of testicular peroxidase and catalase activities as well as by quantification of TBARS and CD of testis.

View Article and Find Full Text PDF