Digits rotation:

X666______X
_66_6_5_5__
______55_5_
99_________
9______88__
99____8_8_7
9_9__8_8__7
99___88___7
___4_____7_
___44___777
X___4_____X

The easiest way to start is to use the 26 diagonal clue. With some help from the 11 you can narrow it down to two choices: either 44-99, or 55-88 (in order from the 26's arrow). If you also keep in mind that there are few ways to obtain 18 and 28 on the top, you should eventually stumble on this way of packing the 4,5,6,9. Then it's just a matter of packing the 8 to avoid every clue, and having the 11 and 13 see exactly one 7.


Divergence:



Most Lasers solve in a similar way: find a really constrained clue, use it, cross it out, rinse and repeat. This one throws a few tricks in thanks to the Ys, but is still pretty similar. First do these clues in order: the 7 in C8, the 3 between C8 and C9 (a nice use of parity), the 5 in C7. In the process of this you can make the realization that the straight segments have to squeeze through the middle without joining too early, which then brings the 8 between C5 and C6 to bear. Then look at: the 6 in C5, the 5 in R1, the 5 in R2 (with the 3 in the last column you can finally finish the top right), the 7 in R7 (whole bottom left done), the 3 between R5 and R6 (combined with the finished 5 in R6), and then use the 6 between C2 and C3 to finish.



Dioxides:

_00S00S0S0_
_S_0_0__00S
_0_S_S0S__0
_S000000_S0
_0_0S0S_000
S0S0____S_S
0000S0__000
0S___00S_S0
___S0S00_0_
S0_00___0S_
00S0S00S0__

Osmium marked as S. Should be easy to see what the molecules are from this. This was in my opinion the most straightforward solve of the bunch if you had a grip on the type. The bottom left is an easy start since it's a dead-end. As you work your way from there, the most helpful realization is that you can't have too many oxygens all in one place, which means any O surrounded by lots of others often can't be an osmium.

couldn't have been explained better...what else to expect from the world champ.....never hit me once to place the 9 in that way..thats why could not solve was trying with 55 88 and trying to adjust the remaning pieces....thnk u melon.......

Riad has now prepared the solution booklet : Link