Limits...
An effective method for substance detection using the broad spectrum THz signal with a "terahertz nose".

Trofimov VA, Varentsova SA - Sensors (Basel) (2015)

Bottom Line: This pulse excites, for example, many vibrational or rotational energy levels of molecules simultaneously.Comparing the absorption and emission spectrum dynamics of a substance under analysis with the corresponding data for a standard substance, one can detect and identify the substance under real conditions taking into account the influence of packing material, water vapor and substance surface.For quality assessment of the standard substance detection in the signal under analysis, we propose time-dependent integral correlation criteria.

View Article: PubMed Central - PubMed

Affiliation: Faculty of Computational Mathematics and Cybernetics, Lomonosov Moscow State University, Leninskiye Gory, Moscow 119992, Russia;. vatro@cs.msu.ru.

ABSTRACT
We propose an effective method for the detection and identification of dangerous substances by using the broadband THz pulse. This pulse excites, for example, many vibrational or rotational energy levels of molecules simultaneously. By analyzing the time-dependent spectrum of the THz pulse transmitted through or reflected from a substance, we follow the average response spectrum dynamics. Comparing the absorption and emission spectrum dynamics of a substance under analysis with the corresponding data for a standard substance, one can detect and identify the substance under real conditions taking into account the influence of packing material, water vapor and substance surface. For quality assessment of the standard substance detection in the signal under analysis, we propose time-dependent integral correlation criteria. Restrictions of usually used detection and identification methods, based on a comparison between the absorption frequencies of a substance under analysis and a standard substance, are demonstrated using a physical experiment with paper napkins.

No MeSH data available.


Related in: MedlinePlus

Fourier spectra of the PWM_1.5 signal and Reference signal, calculated in the time intervals t = [40, 65] (a) and t = [70, 170] (b); spectrum of the signal PWM_1.5 (a1) and Reference signal (b1) for t = [25, 45] ps.
© Copyright Policy
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC4507671&req=5

sensors-15-12103-f027: Fourier spectra of the PWM_1.5 signal and Reference signal, calculated in the time intervals t = [40, 65] (a) and t = [70, 170] (b); spectrum of the signal PWM_1.5 (a1) and Reference signal (b1) for t = [25, 45] ps.

Mentions: Figure 27 shows the Fourier spectra of the PWM_1.5 signal and Reference signal, calculated in the time intervals t = [40, 65] (Figure 27a) and t = [70, 170] (Figure 27b). Frequencies ν = 1.16, 1.4 THz are the spectrum minima of the PWM_1.5 signal in the time interval t = [40, 65] ps (Figure 27a), containing the first sub-pulse; and ν =1.15, 1.4 THz are the spectrum minima of the remote part of the signal t = [70, 170] ps (Figure 27b). At the same time, we do not see minima at these frequencies in the corresponding Reference signal spectrum (Figure 27a), which means the absence of THz radiation absorption from the environment during the first sub-pulse.


An effective method for substance detection using the broad spectrum THz signal with a "terahertz nose".

Trofimov VA, Varentsova SA - Sensors (Basel) (2015)

Fourier spectra of the PWM_1.5 signal and Reference signal, calculated in the time intervals t = [40, 65] (a) and t = [70, 170] (b); spectrum of the signal PWM_1.5 (a1) and Reference signal (b1) for t = [25, 45] ps.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4507671&req=5

sensors-15-12103-f027: Fourier spectra of the PWM_1.5 signal and Reference signal, calculated in the time intervals t = [40, 65] (a) and t = [70, 170] (b); spectrum of the signal PWM_1.5 (a1) and Reference signal (b1) for t = [25, 45] ps.
Mentions: Figure 27 shows the Fourier spectra of the PWM_1.5 signal and Reference signal, calculated in the time intervals t = [40, 65] (Figure 27a) and t = [70, 170] (Figure 27b). Frequencies ν = 1.16, 1.4 THz are the spectrum minima of the PWM_1.5 signal in the time interval t = [40, 65] ps (Figure 27a), containing the first sub-pulse; and ν =1.15, 1.4 THz are the spectrum minima of the remote part of the signal t = [70, 170] ps (Figure 27b). At the same time, we do not see minima at these frequencies in the corresponding Reference signal spectrum (Figure 27a), which means the absence of THz radiation absorption from the environment during the first sub-pulse.

Bottom Line: This pulse excites, for example, many vibrational or rotational energy levels of molecules simultaneously.Comparing the absorption and emission spectrum dynamics of a substance under analysis with the corresponding data for a standard substance, one can detect and identify the substance under real conditions taking into account the influence of packing material, water vapor and substance surface.For quality assessment of the standard substance detection in the signal under analysis, we propose time-dependent integral correlation criteria.

View Article: PubMed Central - PubMed

Affiliation: Faculty of Computational Mathematics and Cybernetics, Lomonosov Moscow State University, Leninskiye Gory, Moscow 119992, Russia;. vatro@cs.msu.ru.

ABSTRACT
We propose an effective method for the detection and identification of dangerous substances by using the broadband THz pulse. This pulse excites, for example, many vibrational or rotational energy levels of molecules simultaneously. By analyzing the time-dependent spectrum of the THz pulse transmitted through or reflected from a substance, we follow the average response spectrum dynamics. Comparing the absorption and emission spectrum dynamics of a substance under analysis with the corresponding data for a standard substance, one can detect and identify the substance under real conditions taking into account the influence of packing material, water vapor and substance surface. For quality assessment of the standard substance detection in the signal under analysis, we propose time-dependent integral correlation criteria. Restrictions of usually used detection and identification methods, based on a comparison between the absorption frequencies of a substance under analysis and a standard substance, are demonstrated using a physical experiment with paper napkins.

No MeSH data available.


Related in: MedlinePlus