Characterization of the double sulfites Cu2SO3Â·MSO3Â·2H2O (M = Cu, Fe, Mn or Cd) by photothermal techniques

Silva, L. A.; Andrade, Jailson B. de; Araújo, C. Moysés; Nakamura, O.; Silva, A. Ferreira da; Massunaga, M. S. O.; Vargas, H.

doi:10.1039/b104834c

Cited by 10 publications

(15 citation statements)

References 16 publications

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“…This feature has also been recently reproduced from photoacoustic measurements. 11 However, the absorption profile is markedly distinct for the Chevreul's salt, in which case the comparison with the series clearly reveals the composite nature of the absorption band in the 400-500 nm range. A new component can be observed at 500 nm, and another one at 1000 nm, in the near-infrared region not accessed by the previous work.…”

Section: Resultsmentioning

confidence: 99%

Electronic Spectra of Chevreul's Salts

Silva¹,

Andrade²,

Toma

2002

J. Braz. Chem. Soc.

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Section: Resultsmentioning

confidence: 99%

Electronic Spectra of Chevreul's Salts

Silva¹,

Andrade²,

Toma

2002

J. Braz. Chem. Soc.

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“…[48][49][50][51][52] The results in Table 3 show the thermal properties determined by photothermic techniques. 47 The thermal diffusivities have values one order of magnitude higher than some semiconductors and porous silicon. [53][54][55] The overall behavior of the thermal parameters seems to reflect the change in the sample structure.…”

Section: Thermal Propertiesmentioning

confidence: 99%

“…To gain a better understanding of the chemical nature of mixed valence compounds, Silva et al 47 investigated several thermal properties, such as thermal diffusivity (α), heat capacity (ρc P ), and thermal conductivity (k), as well as the non-radiative relaxation time (τ R ) and the characteristic diffusion time (τ b ) of the excited state of ions in the double sulfites of the isomorphic series, using photoacoustic spectroscopy (PAS) and the rising temperature method. [48][49][50][51][52] The results in Table 3 show the thermal properties determined by photothermic techniques.…”

Section: Thermal Propertiesmentioning

confidence: 99%

“…This band, in addition to being responsible for the salt's red color, is evidence of the strong Cu(I)-Cu(II) interaction and explains the linear correlation (R = 0.9992) observed when one considers the weighted average (88 pm) of the ionic radius of Cu(I) and Cu(II) (Figure 7). 56 The information concerning the non-radiative relaxation time (t R ) and characteristic diffusion time (t b ) was obtained from measurements of the PA phase angle as a function of the modulation frequency of the maximum absorbance bands (see electronic spectra - Figure 6) using the thermal diffusivity model 51 for a thermally thick sample. 47 The photoacoustically measured relaxation time does not necessarily constitute an appropriate representation of the level initially excited in the absorption process, but rather of the average lifetime of a variety of states before energy is lost in the form of heat.…”

Section: Thermal Propertiesmentioning

confidence: 99%

“…56 The information concerning the non-radiative relaxation time (t R ) and characteristic diffusion time (t b ) was obtained from measurements of the PA phase angle as a function of the modulation frequency of the maximum absorbance bands (see electronic spectra - Figure 6) using the thermal diffusivity model 51 for a thermally thick sample. 47 The photoacoustically measured relaxation time does not necessarily constitute an appropriate representation of the level initially excited in the absorption process, but rather of the average lifetime of a variety of states before energy is lost in the form of heat. Thus, in general, there is a non-unique relaxation pathway consisting of several successive steps, and the measured lifetime is an average lifetime of heat production.…”

Section: Thermal Propertiesmentioning

confidence: 99%

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Isomorphic series of double sulfites of the Cu2SO3.MSO3.2H2O (M = Cu, Fe, Mn, and Cd) Type: a review

Silva¹,

Andrade²

2004

J. Braz. Chem. Soc.

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Embora o primeiro sulfito duplo de valência mista, Cu 2 SO 3 .CuSO 3 .2H 2 O, tenha sido preparado no início do século XIX por M. Chevreul, o interesse por compostos dessa natureza ressurgiu só depois da metade do século XX com a determinação da estrutura cristalina deste composto e a caracterização de seu espectro de absorção na região do infravermelho. Nos últimos anos, os estudos referentes a este tema têm se intensificado, especialmente após a descoberta da possibilidade de substituição isomórfica do Cu(II) no sal de Chevreul por diversos cátions com o mesmo estado de oxidação, gerando uma série de compostos cujas propriedades são fortemente dependentes da natureza do cátion M(II). Devido às suas propriedades interessantes, esses sistemas de valência mista podem ser usados como modelos para identificar intermediários em processos de corrosão atmosférica, bem como para avaliar o papel de metais de transição como catalisadores de autooxidação de S(IV) na conversão do SO 2 na atmosfera.Although the first mixed valence double sulfite, Cu 2 SO 3 .CuSO 3 .2H 2 O, was prepared in the early 19 th century by M. Chevreul, interest in this type of compound was only rekindled in the mid-1960s, when the crystalline structure of Chevreul's salt was determined and its infrared spectrum characterized. Studies of this type of compound have been intensified in recent years, especially after the discovery that the isomorphic Cu(II) in Chrevreul's salt could be replaced by a divalent metal ion, forming an isomorphic series whose properties are strongly dependent on the nature of the M(II) cation. Because of their interesting properties, these mixed valence systems can be used as models to identify intermediates in atmospheric corrosion processes, and to evaluate the role of transition metals as catalysts of S(IV) autoxidation in the conversion of SO 2 in the atmosphere.

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