Infrared and far-infrared spectroscopy of 13CH3OH: TeraHertz laser lines and assignments

Costa, Leverson F. L.; Moraes, João Carlos Silos; Cruz, Flávio C.; Viscovini, Ronaldo Celso; Pereira, D.

doi:10.1016/j.jms.2006.12.002

Cited by 6 publications

(5 citation statements)

References 22 publications

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“…Among several methods to determine the bond structure of composites, Fourier Transformation Infrared spectroscopy (FTIR) has been proven to be a powerful technique and has been widely used as a reliable method [10,11] as it detects the C=C stretching vibrations directly before and after curing of materials. FTIR based on the interaction between electromagnetic radiation and vibrations of the chemical bonds among atoms [12]. FTIR is a way of getting spectra by using an interferometer, and then performing a Fourier Transform (FT) on the interferogram to obtain the spectrum.…”

Section: Introductionmentioning

confidence: 99%

The mechanical properties of nanohybrid and bulk fill posterior composites

Kamalak¹,

Canan²,

Altın³

2018

biomedicalresearch

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Objectives: The objective of this work was to investigate the structural properties, thermal conductivity, Differential Thermal Analysis (DTA), Thermo-Gravimetric analysis (TG), surface homogeneity, microhardness, X-ray analysis of nanohybrid and bulk fill composites. Methods: 108 rectangular specimens were prepared from the following composites: (Estelite Sigma Quick (ESQ), Charisma Smart (CS), 3M Espe Filtek Z 250 (EFZ) and Filtek Restorative (FR)) and subjected to various artificial aging protocols (storage in distilled water for 24 h; thermal cycling, 2 × 3000 cycles 5/55°C). The materials were light-cured for 20 s in a 2 mm × 2 mm × 6 mm teflon mould. The nanoparticles of groups were identified by FT-IR spectroscopy. Surface roughness measurements were carried out by optical microscope, the Vickers hardness number was measured with the stainless steel sheet using a micro-indentation tester (Emco Test Durascan), the heat conductivity of the samples was analyzed by the home made thermal conductivity measurement system, thermogravimetric analysis (DTG, 60-AH, Schimadzu) was used to determine the filler mass fraction. Thermogravimetric analysis was performed in argon atmosphere from 30 to 850°C. Results: It was found that the composites have multiphase component such as metallic dopant and organic binder. Conclusions: The XRD investigation showed that there was a broad halo in the pattern which indicates the organic section in the composites. We found that the temperature dependence of the thermal conductivity of the composites depended on the type of the composites, which are low enough for dental applications. The micro-hardness of the samples was analyzed and the result was compared with literature and it was found that the observed results were in agreement with literature.

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Section: Introductionmentioning

confidence: 99%

The mechanical properties of nanohybrid and bulk fill posterior composites

Kamalak¹,

Canan²,

Altın³

2018

biomedicalresearch

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“…It was on inversion-rotational transitions of NH 3 molecule that laser radiation was generated by French colleagues on our project during optical pumping of ammonia by a quantum-cascade laser [8]. Typically, a CO 2 laser is used as the pumping source of terahertz gas lasers [7,[9][10] as the most convenient and wellstudied source of radiation. In contrast to a CO 2 laser, a molecular CO laser is capable of operating in the mid-IR range almost simultaneously on hundreds of spectral lines in the wavelength range from 2.5 to 8.7 µm, which makes it possible to significantly increase the number of excited molecules and, accordingly, to enrich spectrum of radiation in the terahertz range.…”

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confidence: 99%

THz sources based on frequency conversion of multi-line molecular lasers in nonlinear crystals and on optically pumped molecular lasers

et al. 2018

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“…A 13 CO 2 laser of wide tunability (110 MHz) was used as pump source, and a Fabry-Perot open cavity was used as a FIR laser resonator.The interest on powerful sources of electromagnetic waves in the TeraHertz region (sometimes identified as Far Infrared (FIR)) for applications such as imaging and medical sciences [1][2][3][4][5], has been a strong motivation to reinvestigate CO 2 laser-pumped methanol as active medium for THz laser generation. Optical pumping of polar molecules is one the most efficient techniques to generate cw THz laser lines, and today thousands of discrete emissions, ranging 30µm (10THz) to 3mm (0.1THz), have been observed.…”

mentioning

confidence: 99%

“…An accidental coincidence between a CO 2 laser emission and an infrared molecular absorption is a rather stringent condition in those experiments. The use of isotopic forms of carbon dioxide, as optical laser sources, greatly increases the possibility of those accidental coincidences.In this work we conducted a careful search for new laser lines in CH 3 OH and 13 CH 3 OH optically pumped by a sealed-off 13 CO 2 laser (Lasertch Model LT250 Laser Tube) [1,2]. A Fabry-Perot cavity was used both as an optoacoustic (OA) cell, to record the absorption transitions, and as a TeraHertz laser resonator.…”

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confidence: 99%

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TeraHertz laser generation by optically pumped Polar Molecules

Costa

Viscovini²,

Moraes

et al. 2007

Optical Terahertz Science and Technology

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In this work we report 12 new optically pumped far-infrared (FIR) laser lines from CH 3 OH and 19 from 13 CH 3 OH. A 13 CO 2 laser of wide tunability (110 MHz) was used as pump source, and a Fabry-Perot open cavity was used as a FIR laser resonator.The interest on powerful sources of electromagnetic waves in the TeraHertz region (sometimes identified as Far Infrared (FIR)) for applications such as imaging and medical sciences [1][2][3][4][5], has been a strong motivation to reinvestigate CO 2 laser-pumped methanol as active medium for THz laser generation. Optical pumping of polar molecules is one the most efficient techniques to generate cw THz laser lines, and today thousands of discrete emissions, ranging 30µm (10THz) to 3mm (0.1THz), have been observed. Methyl alcohol and its isotopomers are the best sources of THz laser lines and the CO 2 laser the most widely used source for optical pumping. An accidental coincidence between a CO 2 laser emission and an infrared molecular absorption is a rather stringent condition in those experiments. The use of isotopic forms of carbon dioxide, as optical laser sources, greatly increases the possibility of those accidental coincidences.In this work we conducted a careful search for new laser lines in CH 3 OH and 13 CH 3 OH optically pumped by a sealed-off 13 CO 2 laser (Lasertch Model LT250 Laser Tube) [1,2]. A Fabry-Perot cavity was used both as an optoacoustic (OA) cell, to record the absorption transitions, and as a TeraHertz laser resonator. The FIR laser cavity is formed by two gold-coated copper concave mirrors (R=1.4m) separated by 100 cm. One of these mirrors is fixed while the other is coupled to a micrometer which allows tuning of the longitudinal modes of the FIR laser. For each wavelength measurement, the cavity is scanned over several longitudinal modes and the laser intensity was recorded as function of cavity length. This allows determination of the FIR laser wavelengths with an uncertainty of ±0.5µm. The FIR output power is detected by a Golay cell, after being coupled out by a 45 mirror that can be moved transverse to the axis of the FIR laser cavity. The laser also has an internal eletret microphone used for optoacoustic (OA) detection. The OA signal is used for tuning the CO 2 laser frequency into the active medium absorption. Using this apparatus, we observed 12 new laser lines, ranging from 58.1µm (5.2 THz) to 624.6µm (0.5 THz) from CH 3 OH, and 19 laser lines in the range from 42.3µm (7.1THz) to 717.7µm (0.42 THz), from 13 CH 3 OH. These lines were characterized according to wavelength, relative polarization, relative intensity (very strong (VS), strong (S), medium (M) and weak (W) according to the criteria used in [6]), optimum pressure, and infrared absorption offset frequency. The transferred Lamb-Dip technique was used to measure the absorption offset frequencies [7]. This work was supported by FAPESP, CePOF and CAPES -Brazilian government agencies.

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Infrared and far-infrared spectroscopy of 13CH3OH: TeraHertz laser lines and assignments

Cited by 6 publications

References 22 publications

The mechanical properties of nanohybrid and bulk fill posterior composites

The mechanical properties of nanohybrid and bulk fill posterior composites

THz sources based on frequency conversion of multi-line molecular lasers in nonlinear crystals and on optically pumped molecular lasers

TeraHertz laser generation by optically pumped Polar Molecules

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