PowerPoint-Pr

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Deep Ultraviolet Raman Microspectroscopy Novel
Technique for the Characterization of Phosphorus
in Soil
Christian Vogel, Manfred Ramsteiner and
Christian Adam
BAM Federal Institute for Materials Research and
Testing, Berlin, Germany Paul-Drude-Institut,
Berlin, Germany
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Introduction

• Deep ultraviolet (DUV) Raman microspectroscopy
• Detection of P-Phases in soil
• Advantages and Disadvantages of DUV Raman
  microspectroscopy
• Outlook
• Conclusions

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Deep Ultraviolet (DUV) Raman Microspectroscopy -
Theory
from Asher, Analytical Chemistry, 1993, 65(2),
59A-66A
The electronic resonance enhancement effect can
increase the intensity of the scattered light by
a factor of 106.
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Deep Ultraviolet (DUV) Raman Microspectroscopy
Enhancement Effect
UV/VIS
Guanosine-5-monophosphate
from Dietzek et al., Chapter 2 in Confocal Raman
Microscopy (Springer 2010)
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Deep Ultraviolet (DUV) Raman Microspectroscopy -
Fluorescence
from www.semrock.com/uv-raman-spectroscopy.aspx
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DUV Raman Microspectroscopy of an Alluvial Soil
Alluvial Soil pH(H2O) 7.4 P 0.36
wt. Instrument HORIBA LabRam HR Evolution
Laser 244 nm (Ar-Ion) Lateral Resolution 1 µm
Spectral Resolution 8 cm-1 Time approx. 1h
Imaged Area 15 x 15 µm2
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DUV Raman Spectra of Different Phosphates
AlPO4 (Berlinite)
Hydroxyapatite
Ca-Phytate
Fe-Phytate
Na-Phytate
500
1000
1500
2000
Wavenumber (cm-1)
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Advantages and Disadvantages of DUV Raman
Microspectroscopy

• Advantages
• Detection of organic and inorganic
• phosphates
• High lateral resolution
• (theoretical down to 150 nm)
• Almost no samples preparation required
• No fluorescence appears

• Disadvantage
• Localization of P-phases

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Outlook
Problem of P Localization
Combination with laboratory micro X-ray

fluorescence (µ-XRF)
µ-XRF Mapping of the Alluvial soil
P Ka1
Ca Ka1
Si Ka1
Instrument HORIBA XGT 7200 Area 512 x 512 µm2
Lateral Resolution 10 µm Time 5 min
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Conclusions

• Chemical state of inorganic and organic
  phosphates is detectable
• by DUV Raman Microspectroscopy
• Almost no sample pre-treatment is required
• Combination with µ-XRF make it easier to
  localize P-phases