Molecular spectrometry—milestones for the millennium

Snook, Richard D.

doi:10.1039/a908809a

Cited by 8 publications

(4 citation statements)

References 28 publications

(25 reference statements)

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“…In the last two decades we have witnessed the development of a number of techniques for the non-destructive characterization of the thermal, optical, and structural properties of materials based upon the so-called photothermal techniques [1][2][3][4][5][6]. The photothermal techniques are essentially based upon sensing the temperature fluctuation of a given sample due to nonradiative de-excitation processes following the absorption of modulated or pulsed light.…”

Section: Introductionmentioning

confidence: 99%

Differential thermal lens temperature scanning approach to glass transition analysis in polymers: application to polycarbonate

Rohling

Medina

Bento

et al. 2001

J. Phys. D: Appl. Phys.

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In this paper, mode mismatched thermal lens spectrometry is applied to determine the thermal and optical properties of polycarbonate as a function of temperature. The focus of the experiments was in the temperature range between 120 °C and 170 °C, where the sample glass transitions occurs. In order to validate and evaluate the sensitivity of the proposed method we have also carried out conventional differential scanning calorimetry measurements. The results showed that the temperature dependence of the signal amplitude of the thermal lens provided a better definition in locating the glass transition compared to the differential scanning calorimetry data. In addition, a sharp decrease in the thermal diffusivity values at the beginning of the sample glass transition was observed. According to the Debye model, this change was attributed to the variation of the sample elastic constant throughout the glass transition. Finally, we propose this procedure, called the differential thermal lens temperature scanning approach, as a new method for the investigation of phase transitions in transparent polymers.} \fnm{3}{Author to whom correspondence should be addressed.

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Section: Introductionmentioning

confidence: 99%

Differential thermal lens temperature scanning approach to glass transition analysis in polymers: application to polycarbonate

Rohling

Medina

Bento

et al. 2001

J. Phys. D: Appl. Phys.

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“…Although decades of scientific literature have brought attention to the capabilities of MRR for chemical analysis, conventional techniques (based on absorption) have been limited in terms of measurement speed and sensitivity. [8][9][10][11][12][13] The only previous MRR product line was a microwave spectrometer (8 -40 GHz) offered from Hewlett Packard in the 1960s. [14][15][16] With the introduction of broadband millimeter/submillimeter active multiplier chains (AMCs) that use cascaded Schottky diode multipliers, the room temperature MRR spectrum can be measured in its most favorable frequency region (100-1000 GHz) using stable low frequency microwave synthesizers as the input light source.…”

Section: The Development Of Broadband Ft-mrrmentioning

confidence: 99%

Fourier transform molecular rotational resonance spectroscopy for reprogrammable chemical sensing

et al. 2015

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Molecular rotational resonance (MRR) spectroscopy gives spectral signatures with high chemical selectivity. At roomtemperature, the peak intensity of the MRR spectrum occurs in the 100 GHz -1 THz frequency range for volatile species with mass ≤ 100 amu. Advances in high-power sub-mm-wave light sources has made it possible to implement time-domain Fourier transform (FT) spectroscopy techniques that are similar to FT nuclear magnetic resonance (FT-NMR) measurements. In these measurements, the gas sample is excited by a short (200 ns) excitation pulse that creates a macroscopic sample polarization. The electric field of the subsequent transient molecular emission is detected using a heterodyne receiver and a high-speed digitizer. FT-MRR spectroscopy offers speed and sensitivity improvements over absorption spectroscopy. For chemical analysis, FT-MRR spectrometers combine the benefits of broad chemical coverage typical of gas chromatography -mass spectrometry (GC-MS) instruments and the direct measurement capabilities of infrared gas sensors all in a reprogrammable platform. Pulse sequence measurements can be implemented for advanced spectroscopic analysis. Trace level quantitation of volatile species at ppbv concentration can be performed on the time scale of a minute. In cases where the sample is a complex mixture, a double-resonance pulse sequence can be used to achieve chemical selectivity even in cases where spectral overlap occurs. These measurement capabilities are illustrated using the application of FT-MRR spectroscopy to residual solvent analysis of pharmaceutical products.

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“…Some of them contain general content of the use and application of FT-IR/PAS [22][23][24][25][26][27][28][29][30][31], others are more specific and are devoted to real-time PA parallel detection of products from catalyst libraries [32], step-scan and depth profiling analysis [33][34][35][36][37][38][39][40], the effect of particle size on FT-IR/PAS spectra [41][42][43][44], the temperature effect on PA signal [45], sample emission effects [46], and synchrotron IR/PAS [47]. During a PA measurement the sample is enclosed in a small, tightly closed sample compartment called PA cell [48][49][50][51][52][53][54].…”

Section: Introductionmentioning

confidence: 99%

Application of infrared photoacoustic spectroscopy in catalysis

Ryczkowski

2007

Catalysis Today

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Molecular spectrometry—milestones for the millennium

Cited by 8 publications

References 28 publications

Differential thermal lens temperature scanning approach to glass transition analysis in polymers: application to polycarbonate

Differential thermal lens temperature scanning approach to glass transition analysis in polymers: application to polycarbonate

Fourier transform molecular rotational resonance spectroscopy for reprogrammable chemical sensing

Application of infrared photoacoustic spectroscopy in catalysis

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