Retrieval of interatomic separations of molecules from laser-induced high-order harmonic spectra

We illustrate an iterative method for retrieving the internuclear separations of N$_2$, O$_2$ and CO$_2$ molecules using the high-order harmonics generated from these molecules by intense infrared laser pulses. We show that accurate results can be retrieved with a small set of harmonics and with one or few alignment angles of the molecules. For linear molecules the internuclear separations can also be retrieved from harmonics generated using isotropically distributed molecules. By extracting the transition dipole moment from the high-order harmonic spectra, we further demonstrated that it is preferable to retrieve the interatomic separation iteratively by fitting the extracted dipole moment. Our results show that time-resolved chemical imaging of molecules using infrared laser pulses with femtosecond temporal resolutions is possible.Comment: 14 pages, 9 figure

Numerical investigation of the Rayleigh hypothesis for electromagnetic scattering by a particle

The validity of the Rayleigh hypothesis has been a long-standing issue in the applicability of the T-matrix method to near-field calculations, and despite numerous theoretical works, the practical consequences for numerical simulations have remained unclear. Such calculations are increasingly important in the field of nanooptics, for which accurate and efficient modeling tools are in high demand. We here tackle this challenge by investigating numerically the convergence behavior of series expansions of the electric field around spheroidal particles, which provides us with unambiguous examples to clarify the conditions of convergence. This study is made possible by the combination of alternative methods to compute near-fields accurately, and crucially, the recent improvements in the calculation of T-matrix elements free from numerical instabilities, as such errors would otherwise obfuscate the intrinsic convergence properties of the field series. The resulting numerical confirmation for the range of validity of the Rayleigh hypothesis, complemented by a better understanding of the convergence behavior of the field expansions, is a crucial step toward future developments

Framework for the energetic assessment of South and South-East Asia fixed chimney bull’s trench kiln

One of the major sources of fuel consumption and greenhouse gas emission in South and South-East Asia is brick manufacturing. One of the most commonly implemented technologies for brick manufacturing in this region is the fixed chimney Bull’s trench kiln (FCBTK). This type of technology largely depends on manual labour and is very inefficient when compared to more modern technologies. Because the adoption of more advanced technologies is hindered by the socio-economical background, the much needed innovations in the brick sector are necessarily related to improving/modifying the FCBTK already operational. However, few scientific studies have been conducted on FCBTK probably due to the basic level of technological development. Such studies are however important to systematically and methodologically assess the challenges and solutions in FCBTK. In this study we develop a thermo-energetic model to evaluate the importance of the parameters pertained to FCBTK construction and operation. The prospective of this study is to build an initial thermo-energetic framework that will serve as a basis to investigate possible energetic improvements