Due to its simplicity, H2 constitutes a perfect tool for testing fundamental physics: testing quantum electrodynamics, determining fundamental constants, or searching for new physics beyond the Standard Model. H2 has a huge advantage over the other simple calculable systems (such as H, He, or HD+) of having a set of a few hundred ultralong living rovibrational states, which implies the ultimate limit for testing fundamental physics with H2 at a relative accuracy level of 10^-24. The present experiments are far from exploring this huge potential. The main reason for this is that H2 in its ground electronic state extremely weakly interacts with electric and magnetic fields; hence, H2 is not amenable to standard techniques of molecule slowing, cooling, and trapping. In this project, we propose a completely new approach for H2 spectroscopy. For the first time, we will trap a cold sample of H2. We will consider two approaches: superconducting magnetic trap and ultrahigh-power optical dipole trap (with trap depths of the order of 1 mK). T = 5 K will be achieved with a standard refrigeration technique, and the trap will be filled in situ with the 5 K thermal distribution of the H2 sample. Presently, there is no technology available to cool down the H2 gas sample from 5 K to 1 mK; hence, the only option is to directly capture the coldest fraction. The majority of the molecules that initially fill the trap zone will be lost. However, the high initial H2 density will allow us to trap up to 600 000 molecules. We will do infrared-ultraviolet double resonance H2 spectroscopy referenced to the optical frequency comb and primary frequency standard. The ability to do spectroscopy using a cold and trapped sample will eliminate the sources of uncertainty that have limited previous best approaches and will allow us to improve the accuracy by at least two orders of magnitude. The H2 traps will open up a new way for further long-term progress in the metrology of H2 rovibrational lines.

The goal of the fellowship is to build an ultrasensitive two-dimensional infrared spectrometer and apply it to detection of complex mixtures of trace amounts of volatile organic compounds (VOCs). Third-order spectroscopies using ultrashort pulses, such as 2D IR spectroscopy, are powerful tools for studying both structure and dynamics. They probe the evolution of state-to-state coherences between quantum states and evolution of state populations on femtosecond to nanosecond timescales, in between excitation by ultrashort optical pulses. In terms of molecular properties, 2D IR spectroscopy probes correlations between molecular bonds, which strongly depend on the structure of the molecule as a whole. Compared to linear spectroscopy, which is more bond-specific, 2D IR spectroscopy provides much greater selectivity. Compared to mass spectrometry methods, it is applicable to both small inorganic molecules and to VOCs and easily lends itself to quantitative analysis. 2D IR spectroscopy has not been used for trace-gas analysis up to now because of insufficient sensitivity. This project overcomes this problem by building first of its kind cavity-enhanced 2D IR spectrometer, with up to four orders of magnitude better sensitivity than the previous state of the art, and applying it to vibrational spectroscopy of VOCs. The potential for exploitation of the project outcomes includes breath analysis diagnostics, detection of explosives, narcotics and other trace-gas analysis problems. There are also many potential applications of the outcomes in basic science, in the field of ultrafast dynamics of optically dilute samples (e.g. cold molecular jets or sub monolayer films). Two notable examples include the problem of intramolecular vibrational energy redistribution and the dynamics of hydrogen bond networks. The expertise and unique skills gained during the outgoing phase will be used to establish a new research program in the host institution.

Plant Growth-Promoting Rhizobacteria (PGPR) provide necessary nutrients to the plants and are promising substitute for the chemical fertilizers to promote plant growth and yield. Among various growth promotion properties of PGPR, the ability to fix N2 is important for plant growth. Several media-based techniques are available to screen the N2 fixing bacteria that are tedious, time-consuming and requires significant amount of resources. Therefore, a rapid, cost-effective membrane-based sensor can be a good alternative of these media-based screening methods. Further, a reservoir of diverse microbial communities is present in a unique extreme environment - saline and alkaline lime in Janikowo, Poland. Isolating PGPR from such extreme environments can be useful for mitigating salinity stress on different crops e.g. wheat (Triticum aestivum), which is one of the most important crops in the world facing significant yield loss in the production due to soil salinity. Also, the study of expression of genes that are differentially expressed in wheat upon interaction with PGPR can result in a better understanding of plant-microbe interaction. Hence, the work is proposed in a sequential manner where the membrane-sensor will be prepared to screen N2 fixing bacteria from the samples collected from extreme environments and allowed to interact with wheat plant under saline condition to check its growth promotion effects. Then the most effective strains/consortia for growth promotion will be selected. Finally, Suppression Subtractive Hybridization (SSH) will be performed to study differentially expressed genes in wheat plants upon interaction with selected strains/consortia. The project is expected to develop innovative membrane-based sensor for the detection of N2 fixing bacteria and isolation of novel and potential halotolerant PGPR from anthropogenic extreme environments. SSH based gene profiling study will also be a new approach to understand plant-PGPR interaction.

The acute toxicity and radioactivity of actinide compounds complicate experimental studies of the “soup” of nuclear waste produced in nuclear reactors. This motivates research into computational approaches for determining molecular properties and reactivity of actinide compounds. Unfortunately, the computational resources required by standard quantum chemistry methods grow exponentially with system size, an effect known as the curse of dimension. Since the actinide-containing molecules of relevance to nuclear chemistry contain hundreds of electrons, innovative new approaches that break the curse of dimension must be developed. One such approach models many-electron molecules as collections of noninteracting electron pairs, called geminals. Standard geminal methods are inappropriate for actinide chemistry, however, and must be extended to include (i) computationally efficient ways to account for relativistic effects, (ii) correlations between electrons beyond electron-pairing effects (weak correlation), (iii) electronically excited states, and (iv) the description of unpaired electrons. Specifically, weak correlation will be captured using Coupled Cluster-type approaches, excited states are accessible through an Equation-of-Motion formalism, and open-shell extensions will use generalized quasi-particles as building blocks for the electronic wavefunction. The extended geminal models thus developed will provide the first direct, atomistic, and quantitative computational model for understanding nuclear waste reprocessing and will provide the essential insights that are needed to guide the synthesis of new actinide compounds that can be used to separate actinides from the other components in the “soup” of nuclear waste. The developed models will be robust, computationally cheap, and black-box-like and can be used in many other areas of chemistry and materials physics like lanthanide and transition-metal chemistry, biochemistry, and semiconductor physics.

Modern quantum chemistry reached a remarkable level of description of atoms and molecules and their interactions. Theoretical approaches are particularly helpful when experimental studies are hampered or slowed down due to a trial-and-error approach. In such cases, computational chemistry can provide the much sought-after understanding of molecular properties and reactivity. Unfortunately, conventional wave function models are too expensive for large-scale modeling or require user control on an expert level, while density functional theory may predict unreliable properties. To break the current paradigm of computational chemistry, novel and neat approximations are desirable. One such innovative approach models many-electron systems using electron pair states. Current electron-pair methods are, however, insufficient to reach chemical or spectroscopic accuracy for large molecules of organic electronics and must be extended to (i) accurately describe electron correlations beyond the simple electron-pairing effects, especially in cases where conventional corrections break, (ii) reliably predict molecular properties of both ground and electronically excited states of closed- and open-shell compounds, and (iii) provide an intuitive and black-box platform for non-expert users. These goals will be achieved by (a) dressing electron-pair states with information extracted from multi-reference wave functions using a bottom-up approach, where each step systematically improves the accuracy of the previous model along the ladder of approximation, (b) designing a black-box interface to automatized quantum chemistry calculations using concepts of quantum information theory, and (c) elucidating the structure-properties relationship using the picture of interacting orbitals. The synergy between an inexpensive but reliable quantitative description and the qualitative interpretation of molecular interactions will accelerate the discovery of new materials in organic electronics.