Hello, everyone! I’m back now after a quite long time doing my exams. Then I’m also home now after having two flights from Yogyakarta to my hometown.

I’m going to write not a really long writing because I also have a busy schedule for this holiday. Besides being a committee of some events, I always love to have this ‘cheat time’ to write.

Writing is also a light in the darkness. Just like what I’ve learned from this semester of my study about the fluorescence and phosphorescence. One will light after absorbing energy from S0 to S1 (S is the short term of ‘singlet’). Then, after absorbing the energy, it will directly release the energy also at the same time. The another one, phosphorescence, has a little bit different from the first one.

I’d like to introduce what fluorescence is. You may have likely heard this word in your daily life. You can see this phenomenon in the eyes of a cat. In the night where it’s dark when you meet a cat in the edge of the street, try to focus the flashlight you bring on the cat. Well, you will see the eyes of the cat spray the light. But when you move the flashlight, the light from the cat’s eyes turns off. This happens because the amount of the energy is absorbed in the same amount of the energy that is released. And of course happening at the same time.

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But let’s try to understand the difference when you want to know how phosphorescence works. The energy absorbed to S1 in phosphorescence doesn’t directly release at the same time to S0 like in fluorescence. But there is another process here. The process named ‘intersystem crossing’. This ‘intersystem crossing’ is rarely happened but has a chance to do so. You know that everything has an exception, right? Then, this is a forbidden absorption because it breaks the rule of ‘spin selection rule’ where multiplicity just can happen from S to S and T to T (T is the short term of ‘triplet’ and phosphorescence uses this kind of term). In this ‘spin selection rule’, S to T and T to S are forbidden. It commonly happens from S to S or T to T.

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The Simple Diagram Contains Fluorescence and Phosphorescence Process

Picture from: rsta.royalsocietypublishing.org

In phosphorescence, the energy has that intersystem crossing from S1 to T1. And the energy is saved for a while there. You know that in this case, the energy can be seen in the form of light. The light is dependent on the wavelength that the material has. After knowing this, then you can understand why there is a watch which can alight in the cinema as the light is turned off. The energy comes from elsewhere when you use the watch in your room or in the other places that are not dark. The watch absorbs the energy from the light. But in a few minutes you sit down for watching the cinema, the light of the watch gradually dims. This because T1 goes to T0. And the energy is equivalent to 0. There is no more energy to spray.

This phosphorescence is a forbidden process actually so you can just see this process from the thing that human-made instead of that cat’s eyes that happen naturally.

I never think I will write about this material anyway. But I feel this kind of knowledge is wonderful. The process is quite complex and unique. So I write this. I know that maybe there are some terms that are not familiar to you because you all come from any different backgrounds of study. That’s why I try to write this in a popular way to be easily understood by all of you.

From the title above ‘How to Glow in the Darkness’, maybe you firstly thought about how we as a human being glows in the darkness. From the process I told you, we can understand that to glow in the darkness is something different. When there is no light, you light the others. But a difference sometimes is a problem. Not everyone will like the person who has more and can do more. So it’s called a forbidden process (can happen but usually not). To glow in the darkness is unique so that’s why the watch industry uses this theory to make the watches and sells them expensively. But in the real life, you can ‘glow without leaving’. The light you spray is not for yourself only but the light you make is for everyone. You can help people. You can make them smile. You can make a better change by a small act. You can glow in the darkness. The purpose to glowing in the darkness is not because you want everyone pays attention more to you, but you help them change to be a better one.

For those who find the mistake in this writing, please kindly give your comment and critics. Would like to learn more from you. Opinions and the stuff that have kinds of the fluorescence and phosphorescence process you have are also welcome here to discuss.

I miss your comment seriously! Have a nice holiday. It’s summer in the subtropic area. It’s dry season in the tropics area (my area) but the weather nowadays easily changes in seconds. Sometimes it rains heavily then the sun comes again. Afterward, it drizzles all day. I think climate change is REAL! 😰