scholarly journals Nanosecond photochromic molecular switching of a biphenyl-bridged imidazole dimer revealed by wide range transient absorption spectroscopy

2015 ◽  
Vol 51 (7) ◽  
pp. 1375-1378 ◽  
Author(s):  
Tetsuo Yamaguchi ◽  
Michiel F. Hilbers ◽  
Paul P. Reinders ◽  
Yoichi Kobayashi ◽  
Albert M. Brouwer ◽  
...  
Keyword(s):  
Time Constant ◽  
Absorption Spectroscopy ◽  
Recovery Time ◽  
Transient Absorption ◽  
Thermal Recovery ◽  
Transient Absorption Spectroscopy ◽  
Back Reaction ◽  
Molecular Switching ◽  
Wide Range

We demonstrate that a biphenyl-bridged imidazole dimer exhibits fast photochromism with a thermal recovery time constant of ∼100 ns, which is the fastest thermal back reaction in all reported imidazole dimers.

scholarly journals Excited state dynamics for visible-light sensitization of a photochromic benzil-subsituted phenoxyl-imidazolyl radical

2019 ◽  
Vol 15 ◽  
pp. 2369-2379
Author(s):  
Yoichi Kobayashi ◽  
Yukie Mamiya ◽  
Katsuya Mutoh ◽  
Hikaru Sotome ◽  
Masafumi Koga ◽  
...  
Keyword(s):  
Visible Light ◽  
Rational Design ◽  
Materials Science ◽  
Transient Absorption ◽  
Life Sciences ◽  
Transient Absorption Spectroscopy ◽  
Back Reaction ◽  
Switching Speed ◽  
Wide Range ◽  
Potential Applications

Visible-light sensitized photoswitches have been paid particular attention in the fields of life sciences and materials science because long-wavelength light reduces photodegradation, transmits deep inside of matters, and achieves the selective excitation in condensed systems. Among various photoswitch molecules, the phenoxyl-imidazolyl radical complex (PIC) is a recently developed thermally reversible photochromic molecule whose thermal back reaction can be tuned from tens of nanoseconds to tens of seconds by rational design of the molecular structure. While the wide range of tunability of the switching speed of PIC opened up various potential applications, no photosensitivity to visible light limits its applications. In this study, we synthesized a visible-light sensitized PIC derivative conjugated with a benzil unit. Femtosecond transient absorption spectroscopy revealed that the benzil unit acts as a singlet photosensitizer for PIC by the Dexter-type energy transfer. Visible-light sensitized photochromic reactions of PIC are important for expanding the versatility of potential applications to life sciences and materials science.

scholarly journals Excited State Dynamics for Visible Light Sensitization of Fast Photochromic Phenoxyl-Imidazolyl Radical Complex with Aryl Ketone

2019 ◽  
Author(s):  
Yoichi Kobayashi ◽  
Yukie Mamiya ◽  
Katsuya Mutoh ◽  
Hikaru Sotome ◽  
Masafumi Koga ◽  
...  
Keyword(s):  
Visible Light ◽  
Life Science ◽  
Materials Science ◽  
Transient Absorption ◽  
Transient Absorption Spectroscopy ◽  
Back Reaction ◽  
Switching Speed ◽  
Radical Complex ◽  
Wide Range ◽  
Potential Applications

Visible light sensitized photoswitches have been paid particular attention in the fields of life science and materials science because long-wavelength light reduces photodegradation, transmits deep inside of matters, and achieves the selective excitation in condensed systems.Among various photoswitch molecules, phenoxyl-imidazolyl radical complex (PIC) is a recently developed thermally-reversible photochromic molecule whose thermal back reaction can be tuned from tens of nanoseconds to tens of seconds by rational designs of the molecular structure. While the wide range of tunability of the switching speed of PIC opened up various potential applications, no photosensitivity to visible light limits its applications. In this study, we synthesized a visible light sensitized PIC derivative conjugated with a benzil unit. Femtosecond transient absorption spectroscopy revealed that the benzil unit acts as a singlet photosensitizer for PIC by the Dexter-type energy transfer. Visible light sensitized photochromic reactions of PIC are important for expanding the versatility of potential applications to life science and material science.

Ultrafast excited state relaxation dynamics in a heteroleptic Ir(iii) complex, fac-Ir(ppy)2(ppz), revealed by femtosecond X-ray transient absorption spectroscopy

2021 ◽  
Author(s):  
Jungkweon Choi ◽  
Mina Ahn ◽  
Jae Hyuk Lee ◽  
Doo-Sik Ahn ◽  
Hosung Ki ◽  
...  
Keyword(s):  
Excited State ◽  
Time Constant ◽  
Absorption Spectroscopy ◽  
Internal Conversion ◽  
Transient Absorption ◽  
Transient Absorption Spectroscopy ◽  
Relaxation Dynamics ◽  
X Ray ◽  
Forbidden Transition ◽  
Calculation Results

The experimental and calculation results demonstrate that the 3MLppzCT state generated by the spin-forbidden transition rapidly relaxes to 3MLppyCT through internal conversion process with a time constant of ∼450 fs.

scholarly journals Direct Observation of S2–S1 Internal Conversion in Pyrene by Femtosecond Transient Absorption

1999 ◽  
Vol 19 (1-4) ◽  
pp. 375-379 ◽  
Author(s):  
Frederik V. R. Neuwahl ◽  
Paolo Foggi
Keyword(s):  
Time Constant ◽  
Absorption Spectroscopy ◽  
Direct Observation ◽  
Internal Conversion ◽  
Transient Absorption ◽  
Conversion Process ◽  
Transient Absorption Spectroscopy ◽  
Kinetic Measurements ◽  
State Population ◽  
Femtosecond Transient Absorption

UV pulses of 100 fs at 340 nm are utilised to excite pyrene to the vibrationally cold S2 state. Population and depopulation processes occurring in the S2 state are investigated by transient absorption spectroscopy with a white continuum probe. In the first 400 fs after excitation it is possible to measure the growth and disappearance of a band at 585 nm which is assigned to the S14←S2 transition. As a consequence of the internal conversion process from S2 to S1 state, the disappearance of the 585 nm band and the growth of the transient spectrum due to Sn←S1 transitions can be observed. Kinetic measurements of the S2 decay and S1 growing signals provide an estimate of the rate of internal conversion which occurs with a time constant of 150±50 fs.

Charge-Transfer Dynamics at Ag/Ni-MOF/Cu2O heterostructure in Photoelectrochemical NH3 production

2021 ◽  
Author(s):  
Ying Liu ◽  
Jianmin Lu ◽  
Qianxiao Zhang ◽  
Yajie Bai ◽  
Xuliang Pang ◽  
...  
Keyword(s):  
Charge Transfer ◽  
Absorption Spectroscopy ◽  
Transient Absorption ◽  
Transient Absorption Spectroscopy ◽  
Yield Rate ◽  
Ultrafast Transient Absorption ◽  
Charge Transfer Dynamics ◽  
Ultrafast Transient Absorption Spectroscopy

Decoration of Ag-ultrathin Ni-MOF onside Cu2O was firstly fabricated. The charge-transfer dynamics at heterostructure was in-depth revealed by ultrafast transient absorption spectroscopy. NH3 yield rate (4.63 μg h-1 cm-2) with...

scholarly journals Attosecond x-ray transient absorption spectroscopy in graphene

2021 ◽  
Vol 3 (1) ◽  
Author(s):  
Giovanni Cistaro ◽  
Luis Plaja ◽  
Fernando Martín ◽  
Antonio Picón
Keyword(s):  
Absorption Spectroscopy ◽  
Transient Absorption ◽  
Transient Absorption Spectroscopy ◽  
X Ray
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