Optical property and spectroscopy studies on the selected lubricating oil in the terahertz range

Using Terahertz Time-Domain Spectroscopy to Discriminate among Water Contamination Levels in Diesel Engine Oil

“…The absorption coefficients demonstrated potential for identification and discrimination of water contamination levels of diesel engine oil, particularly at the higher contamination level. The pattern of increasing absorption coefficient with increasing frequency was consistent with studies of other oils, such as transmission fluid (Gorenflo et al, 2006), gasoline engine oil of SF service category (Tian et al, 2009), vegetable oils (Hu et al, 2005) (Li, 2010), and three gasoline engine oil grades (Abdul-Munaim et al, 2015).…”

“…Lubricating oil characterization with THz-TDS includes polyglycol oils with water (Gorenflo et al, 2006), mineral oil with additives (Naftaly et al, 2005), six grades of lubricating oil (Tian et al, 2009), oil base stock and additive (Tian et al, 2012), and vegetable oils (Hu et al, 2005;Li, 2010). Our recent study was able to distinguish among three grades of unused gasoline engine oil and predict viscosity (Abdul-Munaim et al, 2015).…”

“…Examples of refractive indices decreasing across the 0.5 to 1.5 THz range are polyglycol oils by about 0.04 (Gorenflo et al, 2006), four vegetable oils by about 0.02 (Li, 2010), and five plant oils by 0.01 to 0.035 (Ying et al, 2005). Conversely, a gasoline engine oil of service category SF but unreported grade had a refractive index curve that increased by about 0.025 over the range of 0.5 to 1.6 THz (Tian et al, 2009). Although figure 2 appears to show a descending trend with increasing frequency, this is more a function of the y-axis scale.…”

Distinguishing Gasoline Engine Oils of Different Viscosities Using Terahertz Time-Domain Spectroscopy

“…Many applications of THz spectroscopy have been identified [20][21], including petroleum products. Prior research using THz-time-domain spectroscopy (THz-TDS) to distinguish among petroleum and related products includes: three grades of gasoline [22], gasoline and diesel fuel [23], ethanol and gasoline mixtures [24], diesel fuel grades [25], diesel fuel solidifying point [26], biodiesel and base stocks [27], gasoline and diesel fuel [28] inflammable liquids [29], lubricating grease [30], polyglycol oils with water [31], mineral oil with additives [32], six grades of lubricating oil [33], oil base stock and additive [34], and vegetable oils [35][36]. These prior studies demonstrated potential for distinguishing petroleum products, but none evaluated the potential for distinguishing among similar gasoline engine oils of different grades/viscosities.…”

Generating 0.42 THz radiation from a second harmonic gyrotron

“…In China, terahertz waves have become an active research area over the last 10 years [3,4]. Important achievements have been made, such as the THz vacuum electronic devices developed in the University of Electronic Science and Technology of China [5,6], the THz quantum cascade lasers (QCL) developed in the Shanghai Institute of Microsystem and Information Technology [7,8], the THz superconducting detector in the Nanjing University [9,10], the THz optical sources research carried out in Tianjin University [11] and Nankai University [12], the THz time-domain spectroscopy methodology and related application researches carried out in the Capital Normal University [13,14], the THz-material interaction carried out in the Shanghai Jiao Tong University and Institute of Physics, Chinese Academy of Sciences [15], and so on [1618].In this paper, we report on initial experiments on a second harmonic gyrotron developed at the University of Electronic Science and Technology of China (UESTC), which generated radiation at a frequency of 0.423 THz in 5 s pulses, with a power per pulse of about 4.4 kW. To date this is the highest frequency recorded for vacuum electronic devices in China.…”