Research 2: M Simpson

1. Lasers at the Interface of
Chemistry and Physics
Chemistry and Physics
(Biology? Engineering?)
Cather Simpson
Department of Physics
D t t f Ph i
School of Chemical Sciences
c.simpson@auckland.ac.nz
p @
photonfactory.auckland.ac.nz

2. The Photon Factory
Using short and ultrashort laser
pulses ...
...to probe chemistry physics
to chemistry,
... to machine on the μ to nanoscale

3. Important events happens on ultrashort time scales

4. Laser Interactions with Matter
35 fs pulses
100 fs pulses
10 ns pulses

5. Laser Micro‐ and Nanomachining "Research-grade" femtosecond system
⇒ 800 nm (tunable)
⇒ 100 fs (or 35 fs or ps scale)
fs, ps-scale)
⇒ up to 3.5 mJ/pulse (λ dependent)
⇒ 6 μm feature size
⇒ 100 nm limit (Ag on glass λ/8)
"Standard" nanosecond system
⇒ 248 nm; ~10 ns
⇒ up t 10 mJ/pulse
to J/ l
⇒ 2 μm feature size
⇒ 300 nm limit feature size

6. Enabling Technology
Basic, Targeted‐Basic and Applied Research
Engender Technologies, Ltd.

7. 500 μm
1-3 μm

8. The Photon Factory James Tour
& coworkers
P=P photochemistry – a new
twist on an old tale
twist on an old tale
The Photon Factory ‐ Enabling Technology
• robust, reliable source of pulsed laser light
• pulses from nano‐ to femtoseconds
• wavelengths from ultraviolet to infrared
g f f
• low to high pulse energies

9. New photoactive electronic materials
Prof. John
Protasiewicz
Transparent
Protective Film
P t ti Fil
Dr. John Payton
Light Emitting Polymer Film
Dr. Brian Alberding
Dr. Huo‐Lei Peng Dr. Nicole Dickson Protective Film

10. Expanding the toolbox
phospha-PPVs …
polymer OLEDs
photoactive polymers (photonics)
solar energy harvesting?
Prof. John
Protasiewicz
PA P
n
PPV n
n
P
PPE P
n
n

11. Photochemistry and the periodic table
“… it is rather the heavy
elements which behave
normally and not the
ll d t th
more familiar elements
of the first row”
-- W. Kutzelnigg (1984) Angew. Chem. Int. Ed. Engl. 23:272-295

12. Photochemistry and Photophysics of Diphosphenes
Mes
Mes P P Mes
M
But
But
Prof. John Protasiewicz Mes
But P P But j
Prof. Masaaki Yoshifuji
But
But
Dmp = 2,6-Mes2C6H3
Mes* = 2,4,6-tri-t-butylphenyl Urzenius E., Protasiewicz,J.D. (1996)
Main Group Chem. 1:369.
Yoshifuji, M. et al. (1981) JACS 103:4587.

13. Photochemistry and Photophysics of Diphosphenes
What excited states are involved?
What pathways between states are important?
What structural features influence photobehaviour?
P
P
Inversion
P
P
2 P P
P
Dissociative
R R
P P
P
P P P
Rotation R' R'

14. Photochemistry and Photophysics of Diphosphenes
What excited states are involved?
What pathways between states are important?
What structural features influence photobehaviour?
Quantum chemistry calculations
Density functional theory
P
CASPT2//CASSCF P
Inversion
P
P
2 P P
P
??
Dissociative
Ultrafast Spectroscopy
R R
fs-Transient Absorption
P P
impact of P
- ligands P P P
- excitation λ Rotation R' R'
- solvent
fs-Time resolved Raman

15. Ultrafast Transient Absorption & CASPT2//CASSCF

16. Ultrafast Transient Absorption & CASPT2//CASSCF
π– π∗
400 nm excitation ε ∼ 5 − 12,000
rbance
S2
n+ – π∗
Absor
ππ* (S2) singlet state ε ∼ 300 − 1500
τrise = 130 fs
τ1 = 275 fs 300 350 400 450
250 500
τ2 = 20 ps Wavelength (nm)
480 nm excitation
e citation
S1
Mes
n+π* (T1) triplet state P
Mes P Mes
τrise = 230 fs
τ1 = 16 ps Mes
τ2 = 200 ps
DmpP=PDmp

17. Ultrafast Transient Absorption & CASPT2//CASSCF

18. The Photon Factory
Using short and ultrashort laser
pulses ...
...to probe chemistry physics
to chemistry,
... to machine on the μ to nanoscale

20. Current Photon Factory Group
Dr. Chuck Rohde (Physics)
Sarah Th
S h Thompson (Chemistry – PhD student)
(Ch i t t d t)
Julie Kho (Chemistry – PhD student)
Christiaan Hougaard (BSc Hons Physics)
S o s o
Simon Ashforth (BTech Physics)
( ec ys cs) Past Members
Sean Liew (BTech Physics) Laura Harvey (MSc Physics graduate)
Edward Woon Wei An (BTech Physics) Kaidi Liang (BTech Physics)
Jessica Hendy (BA Hons Anthropology) Ling Yan Pang (BTech Physics)
James Park (BSc H
J P k (BS Hons Ch i t )
Chemistry) Amy Lin (MSc. Physics)
(MSc
Josh Bradfield (Mechatronics Engineering) Emma Simpson (Physics exchange)
Center for
Fraser MacMillan (Engineering Science) Hafizah Rahim
Chemical Dynamics
Peter Hosking (Mechatronics Engineering)
g( g g)
Mona Xin Zhu (Biomedical Engineering) Current Collaborators
Hayley Ware (Mechanical Engineering) Prof. David Williams
Matthew Edmond (Engineering Science) Dr. Bryon Wright
Isaac Hamling (Engineering Science) Dr.
Dr Charles Unsworth
Geran Zhang (Biomedical Engineering) Prof. Larry Chamley
Prof. John Protasiewicz
Prof. Terry Gustafson

21. Vice Chancellor’s Strategic Development Fund
Chancellor s
Vice Chancellor's MIRE Program
Faculty of Science
School of Chemical Science & Department of
Physics
Auckland UniServices
National Science Foundation (USA) National
(USA),
Institutes of Health (USA), Department
of Education (USA)