TY - JOUR
AU - Xiao,, Lizhi
AB - Abstract Carbonate-rich rocks cover a primary part of the earth’s petroleum geology reservoir. The study of carbonate has special significance and more effective study methods are now needed. In order to improve the availability of carbonate rock detection, terahertz (THz) spectroscopy was employed to investigate relevant materials in Na2CO3  +  CaCl2  =  CaCO3  +  2NaCl, which is often used to generate CaCO3. By comparing the materials composited with different ions, it can be revealed that Ca2+, CO32− ⁠, Na+ and Cl- have respective absorption features at different frequencies. Furthermore, by utilizing a conservation equation it can be observed that the average refractive indices of Na2CO3 as well as CaCl2 equal those of CaCO3 and NaCl in the entire range. Combining the absorption and refractive effect of the materials in the reaction can comprehensively characterize the different substances and reveal the inner interaction during the reaction. THz spectra can deduce the process of molecule rearrangement in the chemical reaction of long-term rock evolution. Besides, the absorption features of the real carbonate rock collected from the nearest town of Sinan county, Guizhou province in Yunnan–Guizhou plateau validate the peaks’ central frequencies of ions and the principal components of carbonates, which can be in agreement with the SEM-EDS analysis. This research will supply a spectral tool to identify the particles in the rock and deduce an evolution of petroleum carbonate reservoir. carbonate rocks, terahertz spectroscopy, chemical reaction, absorption, refractive 1. Introduction For hundreds of years, petroleum geology has been of wide concern and in recent times has attracted the increasing attention of scientists. In petroleum geology, carbonate reservoirs are extremely significant in the global oil and gas industry. According to a previous report, carbonate reservoir had about 60% of the worldwide reserves of oil and 40% of the world’s gas reserves [1]. In oil–gas reservoir detection, a primary work is to identify the lithology of the rocks. The composites of such rocks include heterogeneous fractured composites caused by great textural variation, which led to complex relationships between the physical properties of the rock geophysical data [2, 3]. As a result, the physical properties of reservoir rocks belong to the solid phase, especially the elemental composite and chemical structures [4]. In the evolution process of geology, a series of physical changes and chemical reactions happened due to long-term natural operation, such as high- and low-temperature switch. The characterization of the materials, which existed in the different stages of evolution, was useful and significant for the investigation of the reservoir rocks and for petroleum exploration [5]. Calcium carbonate (CaCO3) was the primary component of the carbonate rocks in different petroleum geology. Due to the saturation of heavy CaCO3 in nature, carbonate rocks were formed through the precipitation of water [6]. CaCO3 was a kind of inorganic compound; it was neutral and not soluble in water, but soluble in hydrochloric acid. A common method to obtain CaCO3 was to utilize a chemical reaction: Na2CO3+CaCl2= CaCO3+2NaCl1 where Na2CO3, CaCl2, CaCO3 and NaCl were general compounds. The elemental and structural detection of these materials would promote the study of the chemical reaction and the simulated petroleum geology evolution. Herein, we introduced terahertz time-domain spectroscopy (THz-TDS), which was a newly developed spectral method. Owing to the development of ultra-short pulse lasers, semiconductors and sensitive detectors, THz technology advanced rapidly and has been widely used in various fields. THz-TDS, which bridged the gap between infrared and microwave, can provide rich information of intermolecular and intramolecular vibration modes, which cause little damage to carbonate, because of its low photon energy and it gives the amplitude and phase information of the sample simultaneously [7–11]. Therefore, THz technology is a promising tool for both qualitative and quantitative analysis for the reactants and products with high signal-to-noise ratio (SNR). Some of our reports demonstrated that the THz spectrum was very sensitive to the oil–gas resources and pollutants [12–18]. In this research, we undertook an investigation on the reactants and products of a chemical reaction by using the THz-TDS method. The absorption effect revealed the close relationship between the different materials in this reaction. Relative ions had the respective absorption features in the THz range. Meanwhile, the refractive index proved a conservation phenomenon where the average refractive index of the reactants equaled those of the products in the whole range. The results indicated that THz spectroscopy would supply a new selection process for geology evolution detection and really promote the detailed description of petroleum carbonate rock reservoir. 2. Experimental methods The measurement setup is comprised of an atypical THz-TDS system with transmission mode and a femtosecond Ti-sapphire laser (Maitai) from Spectral-Physics. The laser is diode-pump mode-locked with a center wavelength of 800 nm, a pulse width of 100 fs, and a repetition rate of 80 MHz. The laser power is initially attenuated to make the average power equal to ~100 mW. The laser beam is then split by a splitter into two beams, which had relatively higher and lower power. The laser with the higher power is used as the pump beam and that with the lower power as the probe beam. The pump beam is used to generate THz radiation with a p-type GaAs with 〈1 0 0〉 orientation as the emitter. The generated THz pulse with diffusion state is focalized by a hyper-hemispherical lens (HHSL1) and reflected by an indium titanium oxide (ITO1) to obtain collimated THz radiation. It will transmit into the detection system after being focalized by lenses (L2 and L3) and reflected by mirrors (M3 and M4). The probe beam comes from the splitter and transmits through the automatic delay stage, which can move to any set position. The probe beam then reaches the detection system, where the probe beam and THz pulse are collinear and pass through the hyper-spherical lens (HSL); the hybrid beams are focalized onto a 2.8 mm thick 〈1 1 0〉 ZnTe, whose index ellipsoid will be changed by the THz electric field. In this setup, the THz signal is detected and amplified by a lock-in amplifier, which can greatly improve the SNR. A computer was used to control the measurement process and collect the signal data [19]. Sodium carbonate (Na2CO3), calcium chloride (CaCl2), calcium carbonate (CaCO3) and sodium chloride (NaCl) were measured, which belonged to the reactants and products of the reaction (1), where the relative molecular mass equaled 105.99, 110.98, 100 and 58.5, respectively. In this experiment, Na2CO3 and CaCl2 particles have the purity of 99.9%. We initially weighed 10.599 g of Na2CO3 and 11.098 g of CaCl2, and then mixed each with 100 ml of deionized water so that both the Na2CO3 and CaCl2 solutions with a content of 1 mol l-1 were obtained. By blending them together, turbid liquid with the CaCO3 precipitation and NaCl solution can be obtained. It was then filtered by two conventional filter papers. CaCO3 was collected on the paper and NaCl solution flowed into a clean glass. To avoid residue of NaCl on the CaCO3, the CaCO3 was washed and filtered with water three times. Herein, the Na2CO3 and CaCl2 solutions were re-prepared in a similar way to that mentioned above. By being heated in an oven at ~90°C, the Na2CO3, CaCl2 and NaCl solutions would be volatile and crystallize gradually. Then, the solid Na2CO3, CaCl2 and NaCl crystals were collected. Finally, the four materials including Na2CO3, CaCl2, CaCO3 and NaCl were placed in an oven and heated at ~80 °C for 12 h, after which the fine powders of the four materials were obtained for processing. The covered spectral range in the THz region would indeed be broader if thinner pressed discs could be used. For this reason, the size of the Na2CO3, CaCl2 and NaCl pressed discs should be smaller than that of CaCO3 because the CaCO3 has the smallest absorption coefficient in the THz range. Such work would confirm similar ranges of effective spectra in the THz region among the four materials. Therefore, we weighed the dry material powders of Na2CO3, CaCl2, CaCO3 and NaCl, and the mass equaled 1.2, 1.2, 1.5, and 1.2 g, respectively. All the substances with corresponding mass were pressed by a bead machine. The pressure and the time length in the pressing process were 25 MPa and 3 min, respectively. After being manufactured, they were measured by a Vernier caliper to obtain their diameters and depths. The diameters were all 30 mm each, while the thicknesses equaled 0.92, 1.04, 1.46, and 0.91 mm, respectively. In addition, in order to discuss the relation between pure salts and real rock, limestone was collected from the nearest town of Sinan county, Guizhou province in Yunnan–Guizhou plateau, which has beautiful Karst landform in southwest China. The block of rock was first cut into slices with a thickness of ~3.1 mm; the slice was then rubbed down to ensure a smooth surface. The THz spectra of the samples are obtained by scanning the Na2CO3, CaCl2, CaCO3 and NaCl pressed discs one by one, and the reference spectrum is obtained by scanning nitrogen. To minimize the absorption of water vapor and enhance the SNR, the THz beam path was purged with dry nitrogen at room temperature with keeping the humidity below 0.5%. Similarly, the THz-TDS of the rock and its reference were obtained several weeks later. The THz parameters, such as refractive index (n), absorption coefficient (α) and the dielectric constant (r: real part, i: imaginary part) reflect the dispersion and absorption characteristics. After fast Fourier transform (FFT) of the reference and samples’ THz-TDS, the THz parameters can be calculated by the formulas below [20]: n(ω)=ϕ(ω)⋅cω⋅d+12 α(ω)=2k(ω)ωc=2d⋅ln(4n(ω)ρ(ω)⋅(n(ω)+1)2)3 where ω is the frequency, c equals the velocity of light in vacuum, d is the thickness of the sample, k(ω) represents the dispersion index, ρ(ω) and ϕ(ω) are the amplitude ratio and phase difference of the reference and sample signal. 3. Results and discussion A basic investigation was initially performed of the THz dielectric effect of reactants and products of the reaction (1). By using the THz setup shown in figure 1, the THz-TDS of four materials was obtained. Figure 2 shows the THz field signal as a function of time after the transmission of the THz pulses through the nitrogen (reference) and Na2CO3, CaCl2, CaCO3 as well as the NaCl pressed discs. Combined with the reference spectra, there is an obvious attenuation of the peak intensity in the THz-TDS, indicating an evident absorption of the substances in the THz range. Meanwhile, larger delay time lengths of the four materials can also be observed. The effective optical lengths of the THz through the samples were much larger than those through nitrogen. Comparing the samples with each other, Na2CO3 had the minimum peak intensity and time delay, followed by CaCl2, NaCl and CaCO3. The reactants and products had different elemental composition and chemical structure, indicating different vibration modes of the molecules. Some of the vibration modes were caused by intermolecular and intramolecular interaction. The vibrations on the ps timescale were detected due to the sensitivity of the THz-TDS. Figure 1. Open in new tabDownload slide The measurement setup (THz-TDS system). Figure 1. Open in new tabDownload slide The measurement setup (THz-TDS system). Figure 2. Open in new tabDownload slide THz-TDS of the reference and four materials in the chemical reaction. Figure 2. Open in new tabDownload slide THz-TDS of the reference and four materials in the chemical reaction. According to the measured THz-TDS of the reference and four materials, the absorption coefficient α spectra can be obtained by using the formulas (2) and (3). As shown in figure 3, the α spectra of Na2CO3, CaCl2, CaCO3 as well as NaCl were plotted from 0.2–1.9 THz. It is obvious that there was little difference among the four materials in less than 0.5 THz. With the increasing of frequency, the α was gradually augmented with different slopes, which can be described as dy/dx; in 0.5–1.3 THz range. There were no obvious absorption peaks and the absorption of Na2CO3 ranked largest, followed by CaCl2, NaCl and CaCO3, while in the 1.3–1.9 THz range, absorption features were observed in all four spectra. Comparing the four spectra, we can easily identify Na2CO3 with the 1.40, 1.51, 1.60, 1.73 and 1.82 THz absorption peaks. Similarly, CaCl2 can be distinguished by the 1.71 and 1.87 THz absorption peaks. Besides, the 1.72 THz peak position can be observed in the absorption spectra of CaCO3 tablet In addition, we can identify NaCl with the 1.62 and 1.88 THz absorption peaks, and with an additional 1.39 THz peak, which is not so sharp. Based on the analysis of the central frequencies of the absorption peaks, it can be found that several peak locations were very close to each other among Na2CO3, CaCl2, CaCO3 as well as NaCl. For instance, ~1.4 and ~1.6 THz belonged to the peak frequencies of both Na2CO3 and NaCl; ~1.73 corresponded to those of Na2CO3, CaCl2 and CaCO3; and ~1.87 THz belonged to those of CaCl2 and NaCl. Although random noises in the frequency band may have caused some deviations of peak frequencies, several common central frequencies existed in which two materials had similar molecular vibration modes. On the one hand, the four materials can be directly identified according to the respective absorption features in this frequency range, which was in agreement with previous reports [21, 22]. On the other hand, the absorption peaks and their central frequencies indicated that the relationship between the reactants and products in this chemical reaction can be reflected in the THz spectroscopy. Figure 3. Open in new tabDownload slide The frequency dependence of absorption coefficient spectra in the frequency range from 0.21–.9 THz. Figure 3. Open in new tabDownload slide The frequency dependence of absorption coefficient spectra in the frequency range from 0.21–.9 THz. Comparing the THz-TDS of the four materials in figure 2, we find the time delays were different from each other, indicating variant refractive index among them. According to the THz-TDS and formula (2), the frequency dependence of refractive index n spectra can be obtained and are plotted in figure 4, where the frequency ranged from 0.2–1.9 THz. Four kinds of materials exhibited distinctive n. The refractive effect retained the maximum of ~2.29 for the NaCl compared with the others over the entire range, and subsequently ranked CaCl2 (~2.02), Na2CO3 (~1.99) and CaCO3 (~1.81) in decreasing order. The refractive effect of every material remained constant and there was no overlapping phenomenon between the materials. According to figure 4, the products in the chemical reaction of Na2CO3  +  CaCl2  =  CaCO3  +  2NaCl had the largest as well as the smallest refractive index, and the reactants had middle values. In order to compare the refractive information before and after the reaction, we calculated the average index of the reactants and products at all frequencies in a selected range. Then, the relative error ER of the refractive index was obtained in the entire range by using the deviation being divided by average n of the four materials. The detailed ER were depicted in the inset of figure 4 over the entire range. The maximum and minimum ER equaled ~1.7% and ~5.8%, and the average value was ~2.8% over the entire range. Such small error proved that n was unchanged before and after the chemical reaction. Therefore, the n conservation phenomenon was validated in the THz range, indicating that the reaction information was reflected by the THz spectra. Figure 4. Open in new tabDownload slide The frequency-dependent refractive index spectra from 0.2–1.9 THz. The inset reflects the relative refractive error of the deviation before and after the reaction over the whole range. Figure 4. Open in new tabDownload slide The frequency-dependent refractive index spectra from 0.2–1.9 THz. The inset reflects the relative refractive error of the deviation before and after the reaction over the whole range. The study suggests that THz spectroscopy is very sensitive to the materials that exist before and after the chemical reaction. Figures 3 and 4 reflect the absorption and refractive response of the reactants and products of the reaction (1) in the THz range. Absorption peaks were found among the four materials and there were several peaks of the reactants and products at the same frequencies. The central frequencies were related to the characteristic vibration, which was caused by the atomic compositions and the structure. Chemical reaction referred to a process during which the molecules were broken down and new substances were generated by atomic rearrangement. All the materials discussed were ionic compounds and composed of Na+, CO32− ⁠, Ca2+ or Cl-. By comparing the central frequencies of the absorption peaks and ions in their composition, some vibration information can be revealed among the four materials. The absorption features at 1.40 and 1.60 THz belonged to Na+ vibration due to the common frequencies of Na2CO3 and NaCl. Cl- had a characteristic absorption peak at 1.87 THz, because of the common features of CaCl2 and NaCl at this frequency. 1.51, 1.63 and 1.82 THz belonged to the central frequencies of CO32− vibration and 1.71 THz was assigned to Ca2+. It can be observed that CaCO3 had an absorption peak at 1.72 THz, which was different from the central frequencies of CO32− and Ca2+. Here, CaCO3 had the amorphous state due to the powder precipitation. The waveform around the absorption peak exhibited the lower peak height and wider peak width. The ionic bond between CO32− and Ca2+ was relatively strong and the properties of CaCO3 were relatively stable. On the one hand, the absorption coefficient of CaCO3 was smaller than the others in the THz range. On the other hand, the absorption features of the single Ca2+ and CO32− ions discussed above would not reflect in the absorption spectra of CaCO3. In terms of refractive index, the four materials reflected an interesting phenomenon. NaCl crystal had the largest refractive index, followed by CaCl2, Na2CO3 and CaCO3. The refractive index intensities of the four materials in the THz range were different from those in the visible spectra, proving the strong frequency scattering effect of these substances at different frequencies. When passing the inner medium of the materials, THz radiation would interact with the atomic internal electronic system so that the velocity of propagation would slow down. In spite of the difference between the materials, the average refractive index of the reactants and products were unchanged in the different stages of the chemical reaction. The results indicated that the rearrangement of atoms in the four materials had little influence on the scattering effect of the ions in the THz range. Figures 2–4 showed the detailed response of pure binary salts of the reaction (1) in the THz range. In terms of real geological rocks, they are composed of different compounds and have various structures. Carbonate rock often has the characteristics of crystal superposition and orientation. The correct detection of crystal classifications is of great importance. Herein, a real limestone which belonged to a typical carbonate rock was used and discussed. In order to confirm the morphology and chemical composition of the carbonate rock, we initially used scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS) methods. Spray-gold pretreatment was used for the electric conduction of the carbonate surface in the SEM and EDS measurement. Figure 5 showed the EDS spectrum of carbonate rock at the surface, which was shown in the SEM image. According to the EDS spectrum, the mass fraction and atom fraction of the chemical elements were measured and listed in the table. The atom fractions (At%) were pressed in order from large to small as follows: O 44.81, C 18.14, Ca 12.52, Mg 11.12, Si 5.65, Al 2.25, K 1.12, Fe 0.69, in addition to Au, which was introduced by the spray-gold treatment. The real rock was then measured by the THz-TDS system. As shown in the inset of figure 6, the THz-TDS peak intensity EP of rock has an obvious attenuation compared with that of the reference. In order to detect the THz response, the absorption coefficient spectra were calculated in the range from 0.2–1.9 THz. The real carbonate rock has several significant absorption features, whose central frequencies included 1.53, 1.64, 1.72 and 1.82 THz, respectively. By comparing figures 3 and 6, it can be revealed that the principal components of the rock included CaCO3 not only because the absorption peak at 1.72 THz was assigned as the vibration of CaCO3, but because the absorption coefficients of the rock varied from 2–30 cm-1, which were close to those of CaCO3 in figure 3. In addition, according to the discussion above, CO3− had characteristic vibration frequencies such as 1.51, 1.63 and 1.82 THz. In figure 6, absorption features exist at 1.53, 1.64 and 1.82 THz, which correspond with 1.51, 1.63 and 1.82 THz mentioned in figure 3. The EDS results demonstrated that the rock was mainly composed of CaCO3 crystal, other carbonates such as CaMg(CO3)2 and some clay minerals like silicate minerals with Al and Mg elements. Meanwhile, the absorption peaks in the THz frequency range reflected the principal carbonates in limestone. Due to different ions of ionic compounds in rocks, the absorption features in figure 5 also validated the description of the peaks’ central frequencies of cations and anions in their composition. The results of the THz and EDS measurements were in agreement with the actual phenomenon of carbonate rocks [4]. Figure 5. Open in new tabDownload slide SEM-EDS analysis of limestone collected from the nearest town of Sinan county, Guizhou province in Yunnan–Guizhou plateau. Figure 5. Open in new tabDownload slide SEM-EDS analysis of limestone collected from the nearest town of Sinan county, Guizhou province in Yunnan–Guizhou plateau. Figure 6. Open in new tabDownload slide Absorption coefficient α spectra of a typical carbonate rock collected from the nearest town of Sinan county, Guizhou province in Yunnan–Guizhou plateau, China. The inset picture represents the real carbonate and the measurement. Figure 6. Open in new tabDownload slide Absorption coefficient α spectra of a typical carbonate rock collected from the nearest town of Sinan county, Guizhou province in Yunnan–Guizhou plateau, China. The inset picture represents the real carbonate and the measurement. Geological science has attracted the attention of scientists for a long time. Geology mainly refers to the earth’s geological structure, material composition and development history. Its evolution was related to sphere differentiation, physical properties, chemical properties, rock properties, mineral composition, rock as well as rock occurrence, contact relationships, the history of the Earth’s tectonic development, biology evolution, climate change and the condition and distribution of the occurring mineral resources [23]. The results in this study proved the sensitivity of the THz wave to the heteropolar compound and the ion vibration. The chemical reaction information can be revealed in the THz spectra according to the absorption and refractive index. The common carbonate rocks reflect a sensitive response and significant features in the THz range. According to the ion vibration, the principal components of rocks can be rapidly determined, which is in agreement with the analysis of the SEM-EDS. Therefore, the detection of carbonate rocks and their evolution can be realized by THz spectroscopy due to the absorption features and the conservation equation. Such study is worth continuing by combining the spectrum and geology information [24]. 4. Conclusion In summary, the response of THz radiation was discussed regarding the measurement of four materials in the chemical reaction of the reaction (1) and a real limestone collected from Yunnan–Guizhou plateau in China. The absorption and refractive effect were investigated separately, based on THz-TDS. In the selected THz frequency range, absorption and refractive spectra reflected different information regarding these materials. The ions, including Ca2+, CO32− ⁠, Na+ as well as Cl-, had respective absorption intensities and features at different frequencies. Such features can be used to identify the materials. Furthermore, they revealed the inner relationship of the elements among the substances, which was useful to analyze the reaction process. In addition, the refractive index spectra validated a common conservation relation that the average index of the reactants equaled those of the products in the whole range. The combination of absorption and refractive effect in the THz range can really extract the inner element and structure information of the materials in the different stages. By comparing the absorption features of pure materials and limestone, the principal components of real geological rock were characterized by THz-TDS and validated by the EDS results. This research suggested that THz spectroscopy would act as a supplementary tool in the detection of carbonate rocks in petroleum geology. Acknowledgments This work was supported by the National Basic Research Program of China (Grant No. 2014CB744302), the Specially Funded Program on National Key Scientific Instruments and Equipment Development (Grant No. 2012YQ140005), the China Petroleum and Chemical Industry Association Science and Technology Guidance Program (Grant No. 2016-01-07) and the National Natural Science Foundation of China (Grant Nos. 11574401 and 61405259). References 1 de Ceia M A R , Misságia R M , Neto I L , Nathaly A . , 2015 Relationship between the consolidation parameter, porosity and aspect ratio in microporous carbonate rocks , J. Appl. Geophys. , vol. 122 (pg. 111 - 121 ) 10.1016/j.jappgeo.2015.09.012 Google Scholar Crossref Search ADS WorldCat Crossref 2 Vanorio T , Scotellaro C , Mavko G . , 2008 The effect of chemical and physical processes on the acoustic properties of carbonate rocks , Leading Edge , vol. 27 (pg. 1040 - 1048 ) 10.1190/1.2967558 Google Scholar Crossref Search ADS WorldCat Crossref 3 Silva A A , Neto I A L , Misságia R M , Ceia M A , Carrasquilla A G , Archilha N L . , 2015 Artificial neural networks to support petrographic classification of carbonate-siliciclastic rocks using well logs and textural information , J. Appl. Geophys. , vol. 117 (pg. 118 - 125 ) 10.1016/j.jappgeo.2015.03.027 Google Scholar Crossref Search ADS WorldCat Crossref 4 Nabawy B S . , 2015 Impacts of the pore-and petro-fabrics on porosity exponent and lithology factor of Archie’s equation for carbonate rocks , J. Afr. Earth Sci. , vol. 108 (pg. 101 - 114 ) 10.1016/j.jafrearsci.2015.04.014 Google Scholar Crossref Search ADS WorldCat Crossref 5 Li D F , et al. , 2016 Ore geology and fluid evolution of the giant Caixiashan carbonate-hosted Zn–Pb deposit in the Eastern Tianshan, NW China , Ore Geol. Rev. , vol. 72 (pg. 355 - 372 ) 10.1016/j.oregeorev.2015.08.007 Google Scholar Crossref Search ADS WorldCat Crossref 6 Wilford J , de Caritat P , Bui E . , 2015 Modelling the abundance of soil calcium carbonate across Australia using geochemical survey data and environmental predictors , Geoderma , vol. 259–60 (pg. 81 - 92 ) 10.1016/j.geoderma.2015.05.003 Google Scholar Crossref Search ADS WorldCat Crossref 7 Horiuchi N , Zhang X C . , 2010 Searching for terahertz waves , Nat. Photon. , vol. 4 pg. 662 10.1038/nphoton.2010.216 Google Scholar Crossref Search ADS WorldCat Crossref 8 Bao R M , Wu S X , Zhao K , Zheng L J , Xu C H . , 2013 Applying terahertz time-domain spectroscopy to probe the evolution of kerogen in close pyrolysis systems , Sci. China Phys. Mech. Astron. , vol. 56 (pg. 1603 - 1605 ) 10.1007/s11433-013-5085-6 Google Scholar Crossref Search ADS WorldCat Crossref 9 Siegel P H . , 2004 Terahertz technology in biology and medicine , IEEE Trans. Microw. Theory , vol. 52 (pg. 2438 - 2447 ) 10.1109/TMTT.2004.835916 Google Scholar Crossref Search ADS WorldCat Crossref 10 Reklaitis A . , 2013 Monte Carlo study of pulsed terahertz emission from multilayer GaAs/AlGaAs structure , J. Phys. D: Appl. Phys. , vol. 46 145107 10.1088/0022-3727/46/14/145107 OpenURL Placeholder Text WorldCat Crossref 11 Gu L , Zhou T , Tan Z Y , Cao J C . , 2013 Computed tomography using a terahertz quantum cascade laser and quantum well photo-detector , J. Opt. , vol. 15 105701 10.1088/2040-8978/15/10/105701 OpenURL Placeholder Text WorldCat Crossref 12 Feng X , Wu S X , Zhao K , Wang W , Zhan H L , Jiang C , Xiao L Z , Chen S H . , 2015 Pattern transitions of oil–water two-phase flow with low water content in rectangular horizontal pipes probed by terahertz spectrum , Opt. Express , vol. 23 (pg. 1693 - 1699 ) Google Scholar Crossref Search ADS WorldCat 13 Leng W X , Zhan H L , Ge L N , Wang W , Ma Y , Zhao K , Li S Y , Xiao L Z . , 2015 Rapidly determinating the principal components of natural gas distilled from shale with terahertz spectroscopy , Fuel , vol. 159 (pg. 84 - 88 ) 10.1016/j.fuel.2015.06.072 Google Scholar Crossref Search ADS WorldCat Crossref 14 Zhan H L , Wu S X , Bao R M , Ge L N , Zhao K . , 2015 Qualitative identification of crude oils from different oil fields using terahertz time-domain spectroscopy , Fuel , vol. 143 (pg. 189 - 193 ) 10.1016/j.fuel.2014.11.047 Google Scholar Crossref Search ADS WorldCat Crossref 15 Ge L N , Zhan H L , Leng W X , Zhao K , Xiao L Z . , 2015 Optical characterization of the principal hydrocarbon components in natural gas using terahertz spectroscopy , Energy Fuels , vol. 29 (pg. 1622 - 1627 ) 10.1021/ef5028235 Google Scholar Crossref Search ADS WorldCat Crossref 16 Zhan H L , Wu S X , Bao R M , Zhao K , Xiao L Z , Ge L N , Shi H . , 2015 Water adsorption dynamics into active carbon probed by terahertz spectroscopy , RSC Adv. , vol. 5 (pg. 14389 - 14392 ) 10.1039/C4RA14730H Google Scholar Crossref Search ADS WorldCat Crossref 17 Zhan H L , Zhao K , Xiao L Z . , 2015 Spectral characterization of the key parameters and elements in coal using terahertz spectroscopy , Energy , vol. 93 (pg. 1140 - 1145 ) 10.1016/j.energy.2015.09.116 Google Scholar Crossref Search ADS WorldCat Crossref 18 Zhan H L , Li Q , Zhao K , Zhang L W , Zhang Z W , Zhang C L , Xiao L Z . , 2015 Evaluating PM25 at a construction site using terahertz radiation , IEEE Trans. Terrahertz Sci. Technol. , vol. 5 (pg. 1 - 6 ) 10.1109/TTHZ.2014.2378471 Google Scholar Crossref Search ADS WorldCat Crossref 19 Zhan H L , Sun S N , Zhao K , Leng W X , Bao R M , Xiao L Z , Zhang Z W . , 2015 Less than 6 GHz resolution THz spectroscopy of water vapor , Sci. China Technol. Sci. , vol. 58 (pg. 2104 - 2109 ) 10.1007/s11431-015-5938-5 Google Scholar Crossref Search ADS WorldCat Crossref 20 Dorney T , Baraniuk R G , Mittleman D M . , 2001 Material parameter estimation with terahertz time-domain spectroscopy , J. Opt. Soc. Am. A , vol. 18 (pg. 1562 - 1571 ) 10.1364/JOSAA.18.001562 Google Scholar Crossref Search ADS WorldCat Crossref 21 Mizuno M , Fukunaga K , Hosako I . , 2008 Terahertz spectroscopy and its applications to dielectric and electric insulating materials Int. Symp. Electrical Insulating Materials (pg. 613 - 616 ) 22 Rungsawang R , Ueno Y , Ajito K . , 2007 Detecting a sodium chloride ion pair in ice using terahertz time-domain spectroscopy , Anal. Sci. , vol. 23 (pg. 917 - 920 ) 10.2116/analsci.23.917 Google Scholar Crossref Search ADS PubMed WorldCat Crossref 23 Maier A C , Cates N L , Trail D , Mojzsis S J . , 2012 Geology, age and field relations of Hadean zircon-bearing supracrustal rocks from Quad Creek, eastern Beartooth Mountains (Montana and Wyoming, USA) , Chem. Geol. , vol. 312–3 (pg. 47 - 57 ) 10.1016/j.chemgeo.2012.04.005 Google Scholar Crossref Search ADS WorldCat Crossref 24 Koo T , Jang N , Kogure T , Kim J H , Park B C , Sunwoo D , Kim J . , 2014 Structural and chemical modification of nontronite associated with microbial Fe (III) reduction: indicators of “illitization” , Chem. Geol. , vol. 377 (pg. 87 - 95 ) 10.1016/j.chemgeo.2014.04.005 Google Scholar Crossref Search ADS WorldCat Crossref © 2016 Sinopec Geophysical Research Institute
TI - CaCO3, its reaction and carbonate rocks: terahertz spectroscopy investigation
JF - Journal of Geophysics and Engineering
DO - 10.1088/1742-2132/13/5/768
DA - 2016-10-01
UR - https://www.deepdyve.com/lp/oxford-university-press/caco3-its-reaction-and-carbonate-rocks-terahertz-spectroscopy-XMLXsQf7cS
SP - 768
VL - 13
IS - 5
DP - DeepDyve
ER -