The detection of laser-induced structural change of MnO2 using in situ Raman spectroscopy combined with self-modeling curve resolution technique

Widjaja, Effendi; Sampanthar, Jeyagowry T.

doi:10.1016/j.aca.2007.01.008

Cited by 71 publications

(61 citation statements)

References 17 publications

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“…Ettireddy [18] [16] reported that the H 2 -consumption peak at low temperature was associated to the reduction of PtOx crystallites to metallic Pt. Thus, the H 2 -consumption peaks at around 100 and 140°C are associated to the reduction of PtOx [20]. Ce/OMS-2 shows an additive band at 280 cm -1 as compared with that of OMS-2, which was aroused from the size effect when the size of CeO 2 was smaller than 5 nm [21].…”

Section: Sem Micrographsmentioning

confidence: 89%

OMS-2 Catalysts for Formaldehyde Oxidation: Effects of Ce and Pt on Structure and Performance of the Catalysts

Wang

2009

Catal Lett

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OMS-2 (2 9 2 type octahedral molecular sieve) and cerium doped OMS-2 were synthesized by refluxing method. The platinum doped on both samples was prepared by impregnation method for catalytic oxidation of formaldehyde. These catalysts were characterized by BET, XRD, SEM, H 2 -TPR and Laser Raman. Results show that OMS-2 formed needle-shape nanocrystal structure. The addition of Ce before the formation of the OMS-2 structure obstructs the process due to mismatch of the cation size. Rather than into the framework of the structure, the addition of Pt after the formation of the OMS-2 structure was loaded on the surface of catalysts, which strongly influenced the bonding of the Mn-O lattice of OMS-2. The properties of the catalyst structure determine the temperature of complete oxidation of HCHO while Pt promotes this reaction at a lower temperature range due to active surface oxygen species and lattice defects.

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Section: Sem Micrographsmentioning

confidence: 89%

OMS-2 Catalysts for Formaldehyde Oxidation: Effects of Ce and Pt on Structure and Performance of the Catalysts

Wang

2009

Catal Lett

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“…An assignment to Bixbyite can be reasonably proposed, but the large band width hinders definitive conclusion. Furthermore, MnO 2 is very sensitive to the laser power 24 and phase transformations are possible however low is the illumination power used.…”

Section: Phase Assignmentsmentioning

confidence: 99%

Raman identification of natural red to yellow pigments: ochre and iron‐containing ores

Froment

Tournié

Colomban

2008

J Raman Spectroscopy

277

229

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Red and yellow natural (roasted) pigments have been used for millennia. This paper reports on the Raman characterization of about 50 pigments of theÔkhra 'Mathériauthèque' collection from different origins: violet, red, orange, apricot, yellow ochre, Umbrian and Siena earths from France (Puisaye, Ardennes, Vaucluse), Italy (Siena, Sardinia, Venice, etc.), Germany, Sweden, Cyprus and India (Madras). Comparison is made with 'Bengara' Japanese pigments. Goethite is the chromophore of yellow pigments, and haematite (sometimes with magnetite) that of red ochre and earths. Umbrian pigment ('Terre d'Ombre') contains additional manganese oxides. Color shades are related to the content of secondary phases: iron oxides (haematite, goethite, magnetite), quartz, gypsum and anhydrite, calcite, dolomite, alums (jarosites), and to the Fe/M substitution in the haematite structure. The set of secondary phases can be used to confirm a provenance signature (Supplementary Material available).

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“…It is available to analysis the Raman spectra because no first-order Raman peak of MgO exists in the Experimental Section. 12 13 However, the peaks of MnO 2 may not have been be overlapped by a the small component of Mn 3 O 4 because (1) the power of the laser decreased to 4-5 mW on the sample, (2) the peak at 654 cm 1 is separated from the A 1g peak, and (3) the other peak of Mn 3 O 4 at low wavenumbers is weak compared to the E g peak. It is noted that a red shift (shown in Fig.…”

Section: Resultsmentioning

confidence: 99%

Polarized Raman scattering in helimagnetic β‐MnO₂

Chen

et al. 2008

J Raman Spectroscopy

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A rutile b-MnO 2 film was grown on MgO substrate using plasma-assisted molecular beam epitaxy (PAMBE) monitored by reflection high-energy electron diffraction (RHEED). Polarized Raman spectra at various temperatures were obtained to investigate the influence of the helimagnetic structure on the vibrational modes of b-MnO 2 . A red shift of E g modes indicates a gradual formation of spin angles between neighboring Mn 4+ ions. The intensities of the E g and A 1g modes with y-polarized incidence increase remarkably below the Néel temperature. A new view as vibrational mode projection (VMP) indicates the interactions between the magnetic component of incident light and the helimagnetic structure.

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The detection of laser-induced structural change of MnO2 using in situ Raman spectroscopy combined with self-modeling curve resolution technique

Cited by 71 publications

References 17 publications

OMS-2 Catalysts for Formaldehyde Oxidation: Effects of Ce and Pt on Structure and Performance of the Catalysts

OMS-2 Catalysts for Formaldehyde Oxidation: Effects of Ce and Pt on Structure and Performance of the Catalysts

Raman identification of natural red to yellow pigments: ochre and iron‐containing ores

Polarized Raman scattering in helimagnetic β‐MnO₂

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The detection of laser-induced structural change of MnO2 using in situ Raman spectroscopy combined with self-modeling curve resolution technique

Cited by 71 publications

References 17 publications

OMS-2 Catalysts for Formaldehyde Oxidation: Effects of Ce and Pt on Structure and Performance of the Catalysts

OMS-2 Catalysts for Formaldehyde Oxidation: Effects of Ce and Pt on Structure and Performance of the Catalysts

Raman identification of natural red to yellow pigments: ochre and iron‐containing ores

Polarized Raman scattering in helimagnetic β‐MnO2

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Polarized Raman scattering in helimagnetic β‐MnO₂