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X-ray absorption spectroscopy analysis: in situ, operando, in vivo
Iztok Arčon, 2020, objavljeni povzetek znanstvenega prispevka na konferenci (vabljeno predavanje)

Opis: X-ray absorption spectroscopy (XAS) is a powerful tool for characterisation of local structure and chemical state of selected elements in different new functional materials and biological or environmental samples. The XAS spectroscopy is based on extremely bright synchrotron radiation X-rays sources, which allow precise characterisation of bulk, nanostructured or highly diluted samples. With its two methods (XANES and EXAFS) it enables monitoring changes in valence states and local structures of constituent elements during chemical reactions under controlled reaction conditions, and it offers a possibility of a combination of X-ray spectroscopy and microscopy with sub-micron lateral resolution, crucial for analysis of biological samples on sub-cellular level. In this talk some typical examples of advanced XAS analysis will be presented.
Ključne besede: X-ray absorption spectroscopy, EXAFS, XANES, in-situ, operando
Objavljeno v RUNG: 17.10.2020; Ogledov: 3521; Prenosov: 0
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34.
Characterization of organic semiconductor thin layers by transient photocurrent spectroscopy
Nadiia Pastukhova, Egon Pavlica, Gvido Bratina, 2019, objavljeni povzetek znanstvenega prispevka na konferenci

Ključne besede: organic semiconductors, thin layers, spectroscopy
Objavljeno v RUNG: 10.02.2020; Ogledov: 3383; Prenosov: 0
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35.
X-ray absorption spectroscopy set-up for unstable gases: A study of 5p Hydrides
Robert Hauko, Jana Padežnik Gomilšek, Alojz Kodre, Iztok Arčon, 2020, izvirni znanstveni članek

Opis: An absorption cell is constructed for x-ray absorption spectroscopy of reactive, unstable or hazardous gases at room temperature. In conjunction with in-situ micro-synthesis technique relying on handling the gas in syringes it enabled a first measurement of x-ray absorption spectra in the region of K and L edges for the series of hydrides of 5p elements (SnH4, SbH3, TeH2, HI). The signal-to-noise ratio above 103 was achieved, whereby fine detail is discerned in the spectra, in particular the small sharp features above each absorption edge, testifying of coexcitations of outer electrons in the core photoeffect.
Ključne besede: X-ray absorption spectroscopy Micro-synthesis absorption cell Gaseous hydrides Multielectron photoexcitations
Objavljeno v RUNG: 10.02.2020; Ogledov: 3831; Prenosov: 0
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36.
Characterization of organic semiconductor thin layers by transient photocurrent spectroscopy
Nadiia Pastukhova, Egon Pavlica, Gvido Bratina, 2019, objavljeni povzetek znanstvenega prispevka na konferenci

Ključne besede: organic semiconductors, thin layers, spectroscopy
Objavljeno v RUNG: 10.02.2020; Ogledov: 3458; Prenosov: 0
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37.
Determination of Iron in Environmental Water Samples by FIA-TLS
Miha Tomšič, Leja Goljat, Hanna Budasheva, Dorota Korte, Arne Bratkič, Mladen Franko, 2019, izvirni znanstveni članek

Opis: The determination of low concentration of iron in natural waters can be difficult due to the complexity of natural water, but primarily because it requires preconcentration of the sample with solvent extraction. In this work we report on results of thermal lens spectrometry (TLS) coupled to flow injection analysis (FIA) as a highly sensitive FIA-TLS method of iron detection. The concentration of iron redox species was determined using 1,10-phenanthroline (PHN), that forms stable complexes with Fe(II) ions which are characterized by an absorption maximum at 508 nm. The TLS system using a 633 nm probe laser and 530 nm pump laser beam was exploited for on-line detection in flow injection analysis, where a PHN solution was used as the carrier solution for FIA. The concentration of the complexing agent affects the quality of the TLS signal, and the optimal concentration was found at 1 mM PHN. The achieved limits of detection (LODs) for Fe(II) and total iron were 33 nM for Fe(II) and 21 nM for total iron concentration. The method was further validated by determining the linear concentration range, specificity in terms of analytical yield and by determining concentration of iron in a water sample from a local water stream.
Ključne besede: Flow injection analysis, iron concentration, thermal lens spectroscopy
Objavljeno v RUNG: 18.12.2019; Ogledov: 3540; Prenosov: 105
.pdf Celotno besedilo (690,39 KB)

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39.
Photothermal spectrophotometer for meaurements of low absorption in liquid samples
J. Akbar, Humberto Cabrera, Dorota Korte, 2019, objavljeni povzetek znanstvenega prispevka na konferenci

Ključne besede: photothermal spectroscopy techniques, halogen lamps, TL signal
Objavljeno v RUNG: 16.07.2019; Ogledov: 3444; Prenosov: 0
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40.
Trace detection of C2H2 in ambient air using continuous wave cavity ring-down spectroscopy combined with sample pre-concentration
Manik Pradhan, Ruth Lindley, Roberto Grilli, Iain R. White, Damien Martin, Orr-Ewing Andrew, 2008, izvirni znanstveni članek

Opis: Continuous wave cavity ring-down spectroscopy (cw-CRDS) coupled with sample pre-concentration has been used to measure acetylene (C2H2) mixing ratios in ambient air. Measurements were made in the near-infrared region (λ∼1535.393 nm), using the P(17) rotational line of the (ν1+ν3) vibrational combination band, a region free from interference by overlapping spectral absorption features of other air constituents. The spectrometer is shown to be capable of fast, quantitative and precise C2H2 mixing ratio determinations without the need for gas chromatographic (GC) separation. The current detection limit of the spectrometer following sample pre-concentration is estimated to be 35 parts per trillion by volume (pptv), which is sufficient for direct atmospheric detection of C2H2 at concentrations typical of both urban and rural environments. The CRDS apparatus performance was compared with an instrument using GC separation and flame ionization detection (GC-FID); both techniques were used to analyze air samples collected within and outside the laboratory. These measurements were shown to be in quantitative agreement. The indoor air sample was found to contain C2H2 at a mixing ratio of 3.87±0.22 ppbv (3.90±0.23 ppbv by GC-FID), and the C2H2 fractions in the outside air samples collected on two separate days from urban locations were 1.83±0.20 and 0.69±0.14 ppbv (1.18±0.09 and 0.60±0.04 ppbv by GC-FID). The discrepancy in the first outdoor air sample is attributed to degradation over a 2-month interval between the cw-CRDS and GC-FID analyses.
Ključne besede: Rotational Line, Cavity Enhance Absorption Spectroscopy, Adsorbent Trap, Trace Atmospheric Constituent, CRDS Instrument
Objavljeno v RUNG: 15.07.2019; Ogledov: 3514; Prenosov: 0
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