Abstract-Convergence of terahertz radiation and nanotechnology

 

Nicholas B. Lawler, Diwei Ho, Cameron W. Evans,  Vincent P. Wallace,   K. Swaminathan Iyer, 

https://pubs.rsc.org/en/content/articlelanding/2020/tc/d0tc01716g#!divAbstract

There is a growing number of advanced applications that integrate nanotechnology and terahertz radiation. The development of these niche applications has relied on convergent multidisciplinary techniques in conjunction with developments in advanced nanomaterials. The synergistic application of these fields has historically been difficult to realise as the wavelength of terahertz radiation is orders of magnitude larger than the nanoscale. In this review we explore recent developments and unique nanomaterial implementations that have facilitated advancements beyond this size mismatch, resulting in novel techniques offering alternatives to established processes or new avenues of exploration into the study of nanoscale materials and structures.

Abstract-Use of Terahertz Waves To Monitor Moisture Content in High-Pressure Natural Gas Pipelines

Shuting Fan, Kwanghee Jeong, Vincent P. Wallace, Zachary Aman

https://pubs.acs.org/doi/10.1021/acs.energyfuels.9b01112

Pipelines are considered to be the most economical method for large-quantity gas transportation. However, the presence of water in natural gas pipelines causes significant safety and economic issues and must be accurately monitored. In this work, we discuss the feasibility of the emerging technology, terahertz spectroscopy, for monitoring water vapor in natural gas pipelines. We also proposed a novel method by which the transmitted terahertz signal is captured at two different absolute pressures; the differential absorption, subtracted by a quadratic term accounting for the water vapor continuum, was found to be linearly proportional to the partial pressure of water in the vapor phase. Our results indicate that using terahertz waves, as a noncontact spectroscopic technique, combined with our proposed pressure-gradient-based methodology, a minimum of 62 ppm of water vapor can be detected with a path length of 14.7 cm at 100 bar, which satisfies industry requirements.

Abstract-Correlation Between Saturated Fatty Acid Chain-Length and Intermolecular Forces Determined with Terahertz Spectroscopy

 Shuting Fan,  Michael Ruggiero,  Zhengfang Qian,  Vincent P. Wallace

https://chemrxiv.org/articles/Correlation_Between_Saturated_Fatty_Acid_Chain-Length_and_Intermolecular_Forces_Determined_with_Terahertz_Spectroscopy/7553054

We measured crystalline (C-form) saturated fatty acids with even carbon numbers ranging from 12 to 20 using temperature dependent terahertz time-domain spectroscopy (THz-TDS). Absorption features between 0.5 to 2.75 THz were identified at temperatures from 96 K to 293 K, and a systematic red-shift was observed with the increasing carbon chain length. The origins of these absorption bands were uncovered using state-of-the-art ab initio density functional theory (DFT) calculations. Similar vibrational motions in the absorption bands of the different materials highlight the unique role that THz-TDS has for probing weak non-covalent interactions in these materials. Our results showcase the utility of the terahertz region, which is beyond the scope of related vibrational techniques, providing direct evidence of the effect of chain length on the intermolecular interactions of these molecules.

Abstract-Concentration analysis of breast tissue phantoms with terahertz spectroscopy

Bao C. Q. Truong, Anthony J. Fitzgerald, Shuting Fan, and Vincent P. Wallace

https://www.osapublishing.org/boe/abstract.cfm?uri=boe-9-3-1334#top

Terahertz imaging has been previously shown to be capable of distinguishing normal breast tissue from its cancerous form, indicating its applicability to breast conserving surgery. The heterogeneous composition of breast tissue is among the main challenges to progressing this potential research towards a practical application. In this paper, two concentration analysis methods are proposed for analyzing phantoms mimicking breast tissue. The dielectric properties and the double Debye parameters were used to determine the phantom composition. The first method is wholly based on the conventional effective medium theory while the second one combines this theoretical model with empirical polynomial models. Through assessing the accuracy of these methods, their potential for application to quantifying breast tissue pathology was confirmed.

© 2018 Optical Society of America under the terms of the OSA Open Access Publishing Agreement

Abstract- Use of Finite Difference Time Domain Simulations and Debye Theory for Modelling the Terahertz Reflection Response of Normal and Tumour Breast Tissue

• Anthony J. Fitzgerald,
 
• Emma Pickwell-MacPherson,
 
• Vincent P. Wallace mail

• Published: July 10, 2014
• DOI: 10.1371/journal.pone.0099291

http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0099291?utm_source=feedburner&utm_medium=feed&utm_campaign=Feed%3A+plosone%2FPLoSONE+(PLOS+ONE+Alerts%3A+New+Articles)

The aim of this work was to evaluate the capabilities of Debye theory combined with Finite Difference Time Domain (FDTD) methods to simulate the terahertz (THz) response of breast tissues. Being able to accurately model breast tissues in the THz regime would facilitate the understanding of image contrast parameters used in THz imaging of breast cancer. As a test case, the model was first validated using liquid water and simulated reflection pulses were compared to experimental measured pulses with very good agreement (p = 1.00). The responses of normal and cancerous breast tissues were simulated with Debye properties and the correlation with measured data was still high for tumour (p = 0.98) and less so for normal breast (p = 0.82). Sections of the time domain pulses showed clear differences that were also evident in the comparison of pulse parameter values. These deviations may arise from the presence of adipose and other inhomogeneities in the breast tissue that are not accounted for when using the Debye model. In conclusion, the study demonstrates the power of the model for simulating THz reflection imaging; however, for biological tissues extra Debye terms or a more detailed theory may be required to link THz image contrast to physiological composition and structural changes of breast tissue associated with differences between normal and tumour tissues.

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Citation: Fitzgerald AJ, Pickwell-MacPherson E, Wallace VP (2014) Use of Finite Difference Time Domain Simulations and Debye Theory for Modelling the Terahertz Reflection Response of Normal and Tumour Breast Tissue. PLoS ONE 9(7): e99291. doi:10.1371/journal.pone.0099291

Editor: Irene Georgakoudi, Tufts University, United States of America

Received: January 22, 2014; Accepted: May 13, 2014; Published: July 10, 2014