Nanostructured Ag thin film SERS substrate by magnetron ... · Orange juice exposed with Methyl...
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Nanostructured Ag thin film SERS substrate by magnetron sputtering for trace chemical analyses Noppadon Nuntawong, Ph.D. National Electronics and Computer Technology Center (NECTEC)
Transcript of Nanostructured Ag thin film SERS substrate by magnetron ... · Orange juice exposed with Methyl...
Nanostructured Ag thin film SERS substrate by magnetron sputtering for trace chemical analyses
Noppadon Nuntawong, Ph.D.
National Electronics and Computer Technology Center (NECTEC)
Raman
Rayleigh
Photoluminescence
Atomic emission
http://www.photonics.com/Article.aspx?AID=45231
Photon interactions with substances
Vibrational modes for ‐CH2 group
https://en.wikipedia.org/wiki/Infrared_spectroscopy
Symmetricalstretching
Antisymmetricalstretching
Scissoring
Rocking Wagging Twisting
Vibrational Spectroscopy
Infrared spectroscopy
Raman spectroscopy
https://en.wikipedia.org/wiki/Infrared_spectroscopywww.andersonmaterials.com
In the field of spectroscopy, two main techniques are applied in order to detect molecular vibrational motions: Infrared spectroscopy and Raman spectroscopy.
What is Raman scattering?
Raman
Rayleigh
Fingerprint spectrum
Wavelength shift
C. V. Raman (1888-1970)
It is the inelastic scattering of a photon !
A Raman spectrum can therefore be used as a fingerprint for chemical substances
Raman chemical fingerprints
Molecular vibration
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https://en.wikipedia.org/wiki/Molecular_vibration‐ir-‐2.html
Perhaps surprisingly, molecularvibrations can be treated usingNewtonian mechanics tocalculate the correct vibrationfrequencies. The basic assumptionis that each vibration can betreated as though it corresponds toa spring. In the harmonicapproximation the spring obeysHooke's law: the force required toextend the spring is proportional tothe extension.
Hooke’s law
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www.chem.ucalgary.ca/courses/350/Carey5th/Ch13/ch13-‐ir-‐2.html
Hooke’s law
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www.chem.ucalgary.ca/courses/350/Carey5th/Ch13/ch13-‐ir-‐2.html
https://en.wikipedia.org/wiki/Raman_spectroscopy/
Non-destructive and non-invasive method No need of sample preparation Vibrations inactive in IR spectroscopy may be
seen in Raman spectroscopy No problem with aqueous solution Detailed chemical/molecular analysis Spectral information can be used of future
analyses
Classical system Modern Raman imaging system
Handheld Raman
Raman spectroscopy advantages
Raman spectroscopy disadvantages
CRC Press 2009/
The Raman effect is very weak; only 1 in millions of
total scattering
Very low sensitivity
Difficult for fluorescent sample
A trace analysis is almost impossible
Surface-enhanced Raman scattering
EnhancedRaman out
Molecules in plasmon field
Laser in
Au or Ag nanostructure
Improve sensitivity of Raman Spectroscopy!
The Raman effect is very weak; only 1 in a million of total scattering A trace amount of samples may be undetectable
SERS Substrate
Typical substrates
Aggregated colloids (silver or gold)
Roughened silver (gold) surface
Patterned silver (gold) surface
Pros. Cons.
Large enhancement factor
Low enhancement factor
Large enhancement factor
Inexpensive
Low stability, productivity
Expensive
substrate
substrate
OTL Facilities: PVDs
Evaporator Sputtering
Sputtering Sputtering
Self assembled Nano-structural Films
Nano-Structured film
Shadowed region Adatom diffusion
Slanted columnar film
structure
Key Technique; Glancing-Angle Deposition (GLAD)
Compared with commercial SERS chip
OnSpec: NECTEC SERS Chips
Gold Medal Award from INST2017
Some applications of ONSPEC
I. Toxic substances
IV. Narcotics
II. Explosives
www.allfraud.com
III. Fraud documentary
,http://agriculturewire.com
Recent method using GC-MS scan takes > 2 days!
Application I: Toxic substances
SERS takes about 10 minutes!
Trace detection of organophosphates
Orange juice
Orange juice exposed with Methyl parathion (3 ppm)
Demostration of trace detection in orange juice
Application II: Investigating explosive substances
Explosive components
nitrogen-based fertilizerIEDs
Military explosives
Industrial explosives
Trace explosive detections
Trace explosive detections
Explosives analysis (Industrial explosives)
Samples collected from southern provinces1. Buster2. Dyno3. Emalex4. Megablast5. Power Gel6. Origa7. Super Power
Results from ion chromatography indicated some contain perchlorate trace
Trace perchlorate detection by SERS
Forensic Science International, Volume 233, Issues 1–3, (2013), Pages 174-178
Just burn it!
Post-blast experiments
By collecting evidences from witness materials
Goal : Explosive types identified by SERS spectroscopy
Steel
Concrete
TNT ANFORDX
Chlorate
Tetryl
Black powder Power gelPower gel+Chlorate
keep trace evidenceCotton
Vial
SERS spectroscopy
LaserDetector
Post-blast experiments
Post-blast experiments
Post-blast experiments
Using mapping capability of confocal Raman microscope
SERS Mappings technique
Select peaks
Target molecules mapping
Post-blast experiments
Detection of black powder-explosive in acetone at concrete area !
1049
712
Mapping method
Post-blast experiments
5 out of 8 post-blast can be detected by SERS mapping technique
Application III: Fraud documentary
Ram an sh i ft (cm -¹)
Inte
nsity (
co
un
ts)
500 1 000 1 500
0
5 000
10 000
15 000
Ram an shi ft (cm -¹)
Inte
nsity (
co
un
ts)
500 1 000 1 500
0
5 000
10 000
15 000
Ram an sh i ft (cm -¹)
Inte
nsity (
co
un
ts)
500 1 000 1 500
0
5 000
10 000
15 000
Normal Raman spectra of inks on a paper
M. Claybourn, M. Ansell, Using Raman spectroscopy to solve crimes: inks questioned documents
and fraud, Sci. Justice 40 (2000) 261–271
Difference of Raman and fluorescence response indicates modified documentary
Case study: Using Raman spectra to investigate document
Raman shift (cm-¹)
Inte
nsity (
cou
nts
)
500 1 000 1 500 2 000 2 500
2 000
4 000
6 000
8 000
10 000
12 000
14 000
16 000
18 000
20 000Spectrum : Parker 0.8 mm
Allianz c.p.Cross 0113EFaber castel 0.5 mmParker 0.7 mm gelParker 0.8 mmRamy M63Yellow duck
Conventional Raman spectra from blue pen samples collected from local stationery store
Raman shift (cm-¹)
Inte
nsity (
counts
)
500 1 000 1 500 2 000 2 500
10 000
20 000
30 000
40 000
Spectrum : Parker 0.8 mm SERS
Parker 0.8 mmParker 0.8 mm SERS
Raman shift (cm-¹)
Inte
nsity (
counts
)
500 1 000 1 500 2 000 2 500
10 000
20 000
30 000
40 000
50 000
60 000Spectrum : Parker 0.7 mm gel SERS
Parker 0.7 mm gelParker 0.7 mm gel SERS
Raman shift (cm-¹)
Inte
nsity (
counts
)
500 1 000 1 500 2 000 2 500
5 000
10 000
15 000
20 000
Spectrum : Ramy M63 SERS
Ramy M63Ramy M63 SERS
Raman shift (cm-¹)
Inte
nsity (
counts
)
500 1 000 1 500 2 000 2 500
5 000
10 000
15 000
20 000
25 000
Spectrum : Yellow duck SERS
Yellow duckYellow duck SERS
Comparing SERS and conventional Raman spectra
Improved discrimination power for pen ink
Ink colors
Samplenumber
Ink Type Raman active (%) DP
Oil-
based
Water
based gel
Water
based
RS SERS RS SERS
Black
49 65 28 7 20.40 87.75 0.36 0.79 Blue
46 24 54 22 0.00 86.95 0.00 0.95
Red 50 44 42 14 20 98 0.36 0.81
Total 145 133 124 43
Application IV: Narcrotic drugs
Real case: Yabah mixed with an energy drink
sample
methamp
caffeine
Ongoing researches
CRC Press 2009/
Detection of 2-Methylisoborneol (2-MIB) that is
responsible for the unpleasant odor in water
Mycobacterium Tuberculosis (TB)
Dengue virus (DV)
Product Roadmap
Researchers
