Nearly ubiquitous use in sunscreens o Strong UV absorbers needed for adequate sun protection o Photostability is key to long lived & efficient products Avobenzone (4-tert-butyl-4methoxydibenzoylmethane) o Very high near-UV absorption o Degradation pathways lead to less effective protection M. Yamaji and M. Kida, The Journal of Physical Chemistry A 117 (9), 1946-1951 (2013)
cis-trans isomerization isomerization about single bonds to form rotamers enol-keto tautomerization Key intermediate for photodegradation Found in acetonitrile but not in other solvents A. Cantrell and D. J. McGarvey, Journal of Photochemistry and Photobiology B: Biology 64 (23), 117-122 (2001) M. Yamaji and M. Kida, The Journal of Physical Chemistry A 117 (9), 1946-1951 (2013) Stimulated Emission 350 nm
Transient Absorption Ground State Bleach 350 nm Singular value decomposition (SVD) guides global fitting & analysis Reveals two distinct species: o Fast component is assigned as excited state absorption and stimulated emission o Slow component is vibrationally excited molecules in the ground state tES
Small influence by solvent identity suggests primarily intramolecular IVR Sfeir, M. Visualization and Analysis of Broadband Transient Absorption Data IGOR.6.20.x-4.5. April 29, 2013 350 nm 350 nm Methanol
0.42 0.02 0.24 0.04 0.44 0.03 Timescales suggest three distinct non-chelated enol species involved Amplitude factors from fits provide a crude measure of relative yield
Utilized femtosecond resolved transient absorption experiments probing both in the visible and UV to elucidate a more complete picture of the photoisomerization dynamics of Avobenzone Currently working on calculations to back up our observations with respect to solvent dependence of various signals Avobenzone presents a nice target for vibrationally mediated photoisomerization (VIMP) in solution o Perhaps affect the product distribution in the 266 nm probing data? o The 350 nm mx absorption makes pumping at
400 nm an easy wavelength for vib. + elec. Excitation.
You have already used GUSTAR with infinitives (not-conjugated verbs) to say what people like to do. Now, you are going to use GUSTAR to talk about things that people like (not activities). Reminder: Me gusta (I like) ... I don't...
[email protected] 20min ~US > Directions ~exercise? ELECTRICAL MUSCLE STIMULATION (ems) That's where I ve just travelled from to speak to you about this exciting topic, (if you put a magnifying lens here that is what you get, a marvelous spot...
MINI GRAMMAR LESSON: Parts of Speech (Noun) Nouns: Person, place, thing, or idea.. Ms. L shouted, "For freedom!" as she blew off another firework in her backyard, much to the disapproval of her neighbors.
Tenets of The American Dream. Three Central Ideas behind The American Dream: America as the new "Eden"; a land of beauty, bounty and unlimited promise. Optimism justified by the ever-expanding opportunity and abundance that many people have come to expect....
Reprimand (verb/noun) Verb -to scold in a harsh or formal manner. The teacher . reprimanded. us for eating in class. Noun -a strong scolding from someone in authority. We received a . reprimand. for eating in class.
Brazilian drumming workshop and carnival day (Autumn term) Roman trip to Cressing Temple Barns (Spring term) Rye Meads Nature Reserve (TBC) (Summer Term) For our trips to be successful we do rely on parent volunteers. This will not be on...
Ready to download the document? Go ahead and hit continue!