scholarly journals Molecular scale height in NGC 7331

2018 ◽  
Vol 478 (4) ◽  
pp. 4931-4938 ◽  
Author(s):  
Narendra Nath Patra
Keyword(s):  
Scale Height ◽  
Molecular Scale

scholarly journals Theoretical modelling of two-component molecular discs in spiral galaxies

2020 ◽  
Vol 638 ◽  
pp. A66
Author(s):  
Narendra Nath Patra
Keyword(s):  
Spatial Resolution ◽  
Column Density ◽  
Spiral Galaxies ◽  
High Spatial Resolution ◽  
Scale Height ◽  
Molecular Gas ◽  
Thick Disc ◽  
Molecular Scale ◽  
Two Component ◽  
The Ideal

As recent observations of the molecular discs in spiral galaxies point to the existence of a diffuse, low-density thick molecular disc along with the prominent thin one, we investigate the observational signatures of this thick disc by theoretically modelling two-component molecular discs in a sample of eight nearby spiral galaxies. Assuming a prevailing hydrostatic equilibrium, we set up and solved the joint Poisson’s-Boltzmann equation to estimate the three-dimensional distribution of the molecular gas and the molecular scale height in our sample galaxies. The molecular scale height in a two-component molecular disc is found to vary between 50 and 300 pc, which is higher than what is found in a single-component disc. We find that this scale height can vary significantly depending on the assumed thick disc molecular gas fraction. We also find that the molecular gas flares as a function of the radius and follows a tight exponential law with a scale length of (0.48 ± 0.01)r25. We used the density solutions to produce the column density maps and spectral cubes to examine the ideal observing conditions to identify a thick molecular disc in galaxies. We find that unless the molecular disc is an edge-on system and imaged with a high spatial resolution (≲100 pc), it is extremely hard to identify a thick molecular disc in a column density map. The spectral analysis further reveals that at moderate to high inclination (i ≳ 40°), spectral broadening can fictitiously introduce the signatures of a two-component disc into the spectral cube of a single-component disc. Hence, we conclude that a low inclination molecular disc imaged with high spatial resolution would serve as the ideal site for identifying the thick molecular disc in galaxies.

STM of freeze-fracture replicas: Problems and promises

1993 ◽  
Vol 51 ◽  
pp. 68-69
Author(s):  
J. T. Woodward ◽  
J. A. N. Zasadzinski
Keyword(s):  
Scanning Tunneling Microscope ◽  
Organic Materials ◽  
Freeze Fracture ◽  
Atomic Resolution ◽  
Scanning Tunneling ◽  
Tunneling Microscope ◽  
Molecular Scale ◽  
Organic Surfaces ◽  
Metal Layers ◽  
Conductive Surfaces

The Scanning Tunneling Microscope (STM) offers exciting new ways of imaging surfaces of biological or organic materials with resolution to the sub-molecular scale. Rigid, conductive surfaces can readily be imaged with the STM with atomic resolution. Unfortunately, organic surfaces are neither sufficiently conductive or rigid enough to be examined directly with the STM. At present, nonconductive surfaces can be examined in two ways: 1) Using the AFM, which measures the deflection of a weak spring as it is dragged across the surface, or 2) coating or replicating non-conductive surfaces with metal layers so as to make them conductive, then imaging with the STM. However, we have found that the conventional freeze-fracture technique, while extremely useful for imaging bulk organic materials with STM, must be modified considerably for optimal use in the STM.

Oriented Luminescent Nanostructures From Single Molecules Of Conjugated Polymers

2003 ◽  
Vol 771 ◽  
Author(s):  
Adosh Mehta ◽  
Pradeep Kumar ◽  
Jie Zheng ◽  
Robert M. Dickson ◽  
Bobby Sumpter ◽  
...  
Keyword(s):  
Conjugated Polymers ◽  
Polarization Anisotropy ◽  
Emission Pattern ◽  
Spectral Signatures ◽  
Dipole Emission ◽  
Ink Jet ◽  
Molecular Scale ◽  
Jet Printing ◽  
Photochemical Stability ◽  
Printing Techniques

AbstractDipole emission pattern imaging experiments on single chains of common conjugated polymers (solubilized poly phenylene vinylenes) isolated by ink-jet printing techniques have revealed surprising uniformity in transition moment orientation perpendicular to the support substrate. In addition to uniform orientation, these species show a number of striking differences in photochemical stability, polarization anisotropy,[1] and spectral signatures[2] with respect to similar (well-studied) molecules dispersed in dilute thin-films. Combined with molecular mechanics simulation, these results point to a structural picture of a folded macromolecule as a highly ordered cylindrical nanostructure whose long-axis (approximately collinear with the conjugation axis) is oriented, by an electrostatic interaction, perpendicular to the coverglass substrate. These results suggest a number of important applications in nanoscale photonics and molecular-scale optoelectronics.

Programming Technology for Molecular-Scale Computing

2004 ◽  
Author(s):  
Hal Abelson ◽  
Gerald J. Sussman ◽  
Thomas F. Knight ◽  
Radhika Nagpal
Keyword(s):  
Molecular Scale

Introduction to molecular simulations in soft matter

2017 ◽  
Author(s):  
J.-L. Barrat ◽  
J. J. de Pablo
Keyword(s):  
Phase Space ◽  
Numerical Methods ◽  
Theoretical Basis ◽  
Soft Matter ◽  
Relevant Literature ◽  
Coarse Grained ◽  
Soft Interfaces ◽  
Molecular Scale ◽  
Soft Matter Physics ◽  
The Continuum

We describe the main features of the coarse-grained models that are typically useful in modelling soft interfaces, from force fields to the continuum descriptions involving density fields. We explain the theoretical basis of the main numerical methods that are used to explore the phase space associated with these models. Finally, three recent examples, illustrating the spirit in which relatively simple simulations can contribute to solving pending problems in soft matter physics, are briefly described. Clearly, a short series of lectures can offer, at best, a biased and restricted view of the available approaches. Our aim here will be to provide the reader with such an overview, with a focus on methods and descriptions that ‘bridge the scale’ between the molecular scale and the continuum or quasi-continuum one. The objective to present a guide to the relevant literature—which has now to a large extent appeared in the form of textbooks.

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