Fatih Danışman - Middle East Technical University

Molecular level understanding
to new discoveries
Members
Okan Esentürk
Emine Kaya
Enis Arık
Betül Cengiz (Fatih Danışman)
Merve Doğangün
Collaborations
Fatih Danışman
Ayşen Yılmaz
Hakan Altan (Phys)
Bulent Ortaç (UNAM)
TAC FEL Team
Dr. OKAN ESENTÜRK
2009 –
2005 – 2009
2004 – 2005
1999 – 2004
1996 – 1999
Asst. Professor
Fac. Research Asst.
Scientist
Research Asst.
Research Asst.
Chemistry Department, Middle East Technical Univ., Ankara, Turkey
Dept. of Chemistry and Biochemistry, Univ. of Maryland, MD, USA
KT Consulting Inc, CA, USA
Dept. of Chemistry and Biochemistry, Univ. of Maryland, MD, USA
Chemistry Department, Middle East Technical Univ., Ankara, Turkey
Education
• B.S, Chemistry, METU, January 1996.
Advisor: Prof. Dr. Önder Pamuk
ODTÜ
METU
• M.S., Chemistry, METU, May 1998
Thesis: 2- and 3-D Monte Carlo polymerization of five-membered rings.
Advisors: Prof. Dr. H. Önder Pamuk, Prof. Dr. Ersin Yurtsever
• Ph. D., Physical Chemistry, University of Maryland, August 2004
Dissertation: Molecular structure and surface organization: a study of liquid/vapor interfaces
using newly developed sum frequency methods.
Advisor: Prof. Dr. Robert A. Walker
Research Interest
 Linear and Nonlinear Terahertz Spectroscopy
 Second Harmonic Generation and
Sum Frequency Generation Spectroscopy of Surfaces
 Trace Detection
with Fiber Loop Ring-Down Spectroscopy
 FEL Infrared and Far-Infrared Spectroscopy
at Turkish Accelerator Center
Terahertz Spectroscopy (Enis Arık)
Radio Waves
FM
(Hz)
108
Microwave
Mobile
SatTV
Earth2Sat
Radar
Electronic devices
109
1010
1011
giga
THz
1012
tera
Infrared
1013
Visible
ultraviolet
Photonic devices
1014
1015
peta
x-ray
1016
1 THz is ~ 1ps or ~ 300 mm or ~33 cm-1 or ~4.1 meV or ~0.16 kT or ~ 47.6 K
Terahertz Spectroscopy
Balanced
photodetectors
sample
THz generator
(GaP, 150 um or ZnTe 500 um
THz delay
Wollaston
prism
¼ wave
plate
Ti:Sapphire
BBO
Vis Pump – THz Probe
-2 ps
-1 ps
0 ps
0.5 ps
1 ps
5 ps
Pump
40
400 nm
pump delay
20
Signal (mV)
THz detection
(GaP, 150 um or ZnTe 500 um)
(electro-optic Sampling)
0.8 mJ
1 KHz
~60 fs
800 nm
0
-20
-40
-60
Pum 0
pT
ime
(ps
)
5
-8
5 -12
8
4 s)
p
(
0 me
ti
-4 be
o
Pr
THz Uygulamaları
Güvenlik
Görüntüleme
Zararlı Malzeme
ve Patlayıcı
Tayini
Sanayii
Gizli malzeme
ve yazı
karakterizasyonu
Kalite kontrol ve
karakterizasyon
Gıda
maddelerinin
içerik
görüntülenmesi
Medikal
Meyve Sebze
gibi ürünlerin
yetişkinlik tayini
Diş çürükleri,
Kemik kırıkları
Görüntüleme
Tabletlerde etkin
madde ve
homojenlik tayini
Resimler için kaynaklar: http://royalsociety.org/General_WF.aspx?pageid=4294968177; http://www.teraview.com/terahertz; http://www.nlo.ethz.ch/research/TST/thzimaging/; http://www.photonics.com/Article.aspx?AID=16764;
Dünya Genelinde Terahertz Araştırma Grupları ve Merkezleri Dağılımı
ODTÜ Fizik
THz Labı
Kanserli veya
Yanık Hücre
Tayini
Organic
Semiconductors
Sony OLED+OTFT
0.3 mm paper TV
Samsung OLED Display
Citizen clock
0.3 mm x 1.5 m
A prototype, plant-like solar cell by Advanced
Industrial Science and Technology, Japan
Universal Display and LG
structural flexibility, large area coverage,
low temperature processing, and low cost
SHG / SFG Spectroscopy
Interface sums the incoming frequencies
Advantages
SFG = VIS + IR
 Surface specific
IR
 Molecularly specific
 Low conc. sensitivity
 Orientation & conformation
VIS
Vapor
 In situ and non-destructive
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P = P(0) + P(1) + P(2) …
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HH H
H H
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P(2)
I(3)
=c
(2)
E(1) E(2)
a | P(2) | 2 a |c(2)|2 I(1) I(2)
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Interface
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Liquid
SHG / SFG Spectroscopy
Unique capabilities:
i) Recording vibrational spectra of nanoscale interfaces with no interference from bulk
ii) Determination of orientation, conformation and ordering of interfacial species at the
molecular level
What Matters
How does surface structure depend on. . . .
1) molecular structure and/or flexibility?
2) intermolecular forces?
3) the presence of a sub-phase?
Size
Shape
intermolecular ↔ forces
For a predictive understanding of surface organizations
under the influence of anisotropic forces.
SHG / SFG Spectroscopy
Examples of SHG/SFG Applications
• Neat and complex liquid and solid surfaces
(including surfactants, adsorption-desorption processes) .
• Interfaces between liquid crystal phases and polymers.
• Surface growths and underlying mechanisms
• Monolayer phase change studies
• Surface magnetization
• Surface specific microscopy
• Surface specific reaction mechanism
including atmospheric reactions
• Dynamical studies of surface properties and reactions
Fiber Loop Ring-Down Spectroscopy (Betül Cengiz)
Waechter et. al. Sensors 2010, 10, 1716-1742;
Applications:
• Trace Chemical Detection
• Pressure/Temperature Sensor
• Gas Concentration
• Microfluidics
• Biomolecules (protein analysis)
• Stress/Strain
• Refractive Index
FLRD
methane sensor
(gas cell).
Chuji Wang, Sensors 2009, 9, 7595-7621;
FEL Parameters
TAC IR Free Electron Laser
FEL–I
FEL–II
Wavelength [μm]
2– 30
18 – 250
Pulse energy [μJ]
~10
~8
Peak Power [MW]
10 max
8 max
1-10
1-10
Pulse width [ps]
• A pulsed laser source in the infrared (IR) and far-infrared (FIR) covering a very large range (2 - 250 mm)
• Discrete frequencies with a picosecond pulsewidth
• Large (5-6 mm) beam diameter
• Bandwidth on the order of 0.1% (IR) - 1% (FIR) (worst-case) of the center frequency
• Flexibility on repetition rate from quasi-CW to 1 kHz
FEL Wavelengths
Many Thanks
¿ Questions ?
Uzungöl, Trabzon
http://physweb.bgu.ac.il/COURSES/Astronomy1/Graphics/solar_spectrum.png